Walter Torres says he's glad that next year he will be a senior at Georgetown University. "If I was just coming here now," he explains, "I don't see how I could make it."

The cost of a year's education is going up next fall to $11,000. Federal aid, which Torres and 90 percent of Georgetown's other undergraduates receive, is threatened by budget cuts.

"It's getting very tight," says Torres, whose father, a pothole repairman in New York City, earns about $22,000 a year. "Maybe if I don't have the money, I'll have to drop out for a while and work as a waiter."

Georgetown's financial aid director, Kenneth Kohl, says he's worried, too.

"It's going to be difficult, but I think we'll be able to live with it the aid reductions next fall," Kohl says. But after that, if Congress "makes the cuts that Reagan wants, it will be well nigh impossible to stay the way we are."

Since passage of the Middle Income Student Assistance Act of 1978, federally supported aid to college students has almost tripled, dramatically changing the way Americans pay for higher education. This year $11.8 billion in government subsidized loans and grants are going to about half of the nation's 12 million college students--middle-income as well as poor--compared to just one in seven, virtually all low-income, who had federal help a decade ago.

Though Georgetown is more selective and expensive than most, the university provides a good example of what happened as federal aid soared. Middle-class students borrowed heavily, more low-income and minority students enrolled, tuition rose, parents had to pay less of their own money for their children's education, and, in some cases, low-interest loan money was used for high-interest-paying investments.

Late last year Congress voted a 5.4 percent cut in the main student aid programs. A needs test was imposed on low-interest loans for families earning over $30,000. When the Reagan administration, concerned over what it called runaway costs, last month proposed much more drastic reductions for 1983-84, it set off a wave of bitter denunciation by college administrators and students and created considerable uncertainty and fear.

Higher education officials believe it unlikely that Congress will approve major cuts. Indeed, last week the House Appropriations Committee voted against any further reductions in eligibility for student loans.

"The higher education community rolled over and played dead last year," said Michael B. Goldstein, a lobbyist for one group. "This year they've played 'Chicken Little,' but they've done it very effectively."

No matter what Congress eventually does, the debate has focused attention on the impact that federal student aid has had.

At Georgetown the number of undergraduates receiving subsidized loans rose from about 1,400 in 1978-79, just before a $25,000 income ceiling for getting them was eliminated, to 4,500 this year, or 90 percent of the U.S. citizens enrolled. Last fall, the number borrowing increased by 1,500.

The loans of up to $2,500 a year carry just 9 percent interest, compared to 14 to 18 percent for consumer borrowing. It's still 7 percent for those who first borrowed before 1981, and the government pays all the interest until six months after a student leaves college. Over the past four years the amount borrowed by Georgetown undergraduates climbed from $2.6 million to $9 million.

Other federal aid--in the form of grants, subsidized student jobs and National Direct Student Loans with interest rates of 3 to 5 percent--rose about 75 percent to $3.6 million. Those with family incomes up to $27,000 are eligible for some of this aid, which now is received by 30 percent of Georgetown undergraduates,

Meanwhile, minorities increased from 12 percent of undergraduate enrollment in 1978 to 15 percent last fall, though the rise had been even steeper--up from 7 percent in 1977--just before federal aid soared. Also, with a major infusion of its own funds, Georgetown became one of just a few dozen colleges in the country to guarantee that the full financial need of all accepted students will be met.

Most students at Georgetown, like those at other selective colleges, still are middle-class or above. Half the current freshmen come from families earning more than $34,100, according to data compiled by the College Board. Some 31 percent had incomes of $50,000 or more, compared to 6.7 percent in that bracket nationwide.

Georgetown officials say the middle- and upper-income profile would have been more pronounced had it not been for federal aid.

"Since 1978 we've been able to meet full need, and we're getting a more diversified group of students," said admissions director Charles Deacon. "I'm afraid that if the aid is cut, we'll find it harder, but for this coming fall's class, we're going to continue to do it."

Tuition at Georgetown has gone up two-thirds since 1978, including an increase of 18.8 percent next fall, its steepest jump ever. Across the country tutition rises averaged a record 13 to 14 percent in 1981, well above inflation. Lawrence E. Gladieux, exeuctive director of the College Board Washington office, said the large increases may partly be a "catch-up" for relatively modest rises in the mid-1970s, but he suggested that the big jumps in federal aid "may have paved the way" for the boosts.

To match Georgetown students with the aid money available Kohl and his assistants pore over printouts and application forms in a cluttered basement office in White-Gravenor Hall.

With enough aid for all who need it, the process has become much more mechanical than it used to be, Kohl said. First, a standard expense budget is computed, then an expected family contribution, which is calculated from data that parents submit to the College Board. The difference is called remaining need, and Kohl fills it in with a combination of federal loans, grants and subsidized jobs, plus Georgetown's own money if more is needed.

For next year the budget will come about $11,000, including $6,830 for tuition, $2,920 for room and board, $1,000 for books and personal expenses, and an estimated $250 for travel between home and college.

Kohl estimates that when the cuts voted by Congress go into effect next fall, federal aid at Georgetown will drop by about 11 percent. The decline is steeper than the 5.4 percent reduction nationwide because Georgetown has proportionately more middle-income students, the group most affected by the cuts.

To make up the gap, Kohl said, the university is trying to establish its own $10 million loan fund. It is also launching a major fund-raising drive, like many other universities, and starting a new student job-hunting service.

In addition, about $200 out of next fall's $1,080 tuition increase will go to Georgetown's own scholarship funds. These are scheduled to rise by 27 percent to $5.1 million. About 35 percent of undergraduates now get university scholarships. Altogether, about $925 out of next year's $6,830 tuition bill will be used for financial aid.

"You might call this the Robin Hood approach," said admission director Deacon. "You charge more to those who can afford to pay and plow some of it back to help the others. But obviously that has its limits."

Some middle-class parents who don't have enough money to pay all the bills probably will have to take out auxiliary guaranteed loans, Deacon said. These loans are available regardless of income, at 14 percent interest for which the borrower is responsible almost immediately.

To get a 9 percent loan students whose families earn more than $30,000 a year will have to meet a needs test. But because the test is linked to what a college costs, at high-priced Georgetown the full $2,500 probably will be available to those with income up to $55,000.

This year's 9 percent loan recipients at Georgetown include one student whose parents are both physicians, each earning over $50,000 a year. Another is the son of an advertising executive with a suburban home, a big-city apartment, and an income last year of over $150,000.

"It's good to be a little independent of your parents," said the physicians' son, who asked that his name not be used. "With interest like that, why not?"

Another student interviewed at the university said he used his loan to travel in Europe. And another said it helped buy her car. Several said that because of the loans they had been able to invest in high-interest money market funds, a practice that administration officials say is widespread across the country.

It is these examples that administration officials point to in arguing for reductions in federal aid, even as they acknowledge that lower-income students need government assistance.

Nationwide, according to data compiled by the U.S. Education Department, the average contribution of parents to a freshman's education dropped by 6.2 percent from 1978 to 1980 as federal aid soared. The drop was greatest for the middle class group--13.8 percent for those earning $25,000 to $40,000.

Education Secretary Terrel H. Bell, arguing for the proposed cutbacks, says the figures show that parents are taking less financial responsibility than they used to for their children's education.

Under the administration's proposals all 9 percent loans would be limited by need no matter how low the family income, interest subsidies for undergraduate loans would end two years after they leave college instead of the current 10, and graduate students would be eligible only for 14 percent loans. Grant programs would be cut more than 40 percent, with overall student aid costs dropping about one-third in 1983. Bell said this would force those who can to pay more and end misuse of funds while targeting aid on the neediest.

Georgetown's Deacon said that, while some students may misuse federal aid, most need what they get. With the sharp cuts sought by Reagan, he said, the university probably would have to end its policy of promising full aid for all students in need.

Around the country very few colleges can make this promise now. Instead, most give their own funds to the needy students they most want to enroll. Other needy students are admitted, but don't get enough scholarship money to meet all expenses. In effect, if aid is cut, the less bright among the more needy would probably be forced out.

"We used to give aid from the top down until we ran out of funds," Deacon said. "It was an agonizing and horrendous process . . . . Now we don't use money to buy a kid. But if there's not enough for everybody, that's what we might have go back to."