Braudilio Torrez, a tomato packer who left Cuba in the Mariel boatlift four years ago, left behind nine brothers who are waiting to follow him to Miami.

"I have the impression they will come," he said. "I got a letter from one of them who said that if there was a possibility to get out, he would be the first one here."

Torrez, 31, is an example of what has prompted fear and indignation among many residents and public officials in the streets and offices of Miami. As Cuba and the United States announce agreement on renewed emigration from Fidel Castro's nearby island, the specter has arisen of new strains on south Florida's resources and another injection of Cubans into a city already more Latin than Deep South.

Gov. Robert Graham has written President Reagan urging the administration to make plans to pay for any extra expenses Florida could incur in absorbing the new immigrants. He has called on federal agencies to send representatives to a special conference early next year to coordinate strategies on how to handle the new arrivals.

"If we're going to be expanding the size of Miami and Dade County by 300,000 and we know about it, let's take advantage of that," said Pat Riorden, Graham's spokesman in the state capital of Tallahassee. "Let's not do it in a panic."

Graham and the Miami and Dade County governments have not forgotten what happened in 1980 when the Carter administration allowed an estimated 125,000 Cubans to enter the United States from the Cuban port of Mariel. The federal government, which called the boatlift a "Freedom Flotilla," welcomed the arrivals as refugees from Castro's communist rule. But when some turned out to be criminals, mental patients and unemployables, local Florida governments were left to deal with much of the problem.

"The last time the federal government took a decision like this, we ended up with $150 million in unpaid bills," Riorden said.

Reflecting this attitude, Dade County Manager Merrett Stierheim last week ordered county employes, many Cuban, to stop helping Mariel refugees register for permanent residence. Immigration is a federal problem, he argued, and should be resolved with federal tax dollars.

The Reagan administration, interpreting the 1966 Cuban Adjustment Act, ruled Nov. 19 that Mariel refugees could begin this month registering for permanent residence and, eventually, citizenship. Previously, most have been living in the United States in a legal limbo officially classified as "Cuban-Haitian Entrants -- Status Pending."

This not only gives the Marielitos, as they are called here, a right to continue living in the United States and travel in and out of the country. The Cuban-U.S. agreement to renew normal immigration, also means that as permanent residents, the Cubans will be able to bring to the United States spouses, parents and unwed children under 21 within limits of a 20,000-a-year U.S. immigration quota for Cuba.

As citizens, they will be able to bring these family members without waiting to get into the quota line, and also will have the right to bring in other family members within the 20,000 quota, including Torrez' nine brothers.

Since the five-year wait for citizenship begins with entry rather than resident status, immigration officials explain, many Mariel refugees would be eligible to become naturalized citizens before the end of the summer or whenever their residency paperwork is finished.

With between 90,000 and 100,000 Mariel refugees living in the Miami area, that could mean an influx of up to 300,000 Cubans in the years to come, officials at the Immigration and Naturalization Service have estimated. The process could take up to 20 years, they say, but even over time, this could have a profound impact on the demography of Miami, whose 350,000 residents are already 60 percent Cuban. Many non-Latin residents -- "Anglos," they are called here -- view this with distaste.

Graham has demanded that the agreement with Cuba take into account what his office has calculated are 669 Mariel refugees in Florida state prisons and 541 in Florida county jails, including more than 400 in Dade County, for crimes committed since their arrival.

The agreement between U.S. and Cuban negotiations would cover return to Cuba of about 2,500 Mariel refugees found "excludable" on arrival in 1980 and jailed in federal prisons because of their records in Cuba.