There should be little doubt that General Secretary Mikhail Gorbachev's historic visit to Washington to sign a treaty on intermediate-range nuclear forces is motivated in large part by his needs and desire for help in modernizing the Soviet economy.

A status report by American intelligence agencies on the effects of Gorbachev's perestroika program to restructure Soviet society forecasts economic growth for the years 1987-1990 at no better than 2 to 3 percent, below the 1986 achievement of 4.2 percent (the highest in a decade) and well under Gorbachev's stated goal of a 4 percent average for 1986-1990.

To be sure, 2 to 3 percent growth is no worse than that in much of the western industrial world. But the Soviet consumer is being left far behind. Against the 4.2 percent record for 1986, per capita consumption gained only 1 percent, in part because of the drop in legal sales of alcohol in the Soviet Union.

Many recent returning American and European visitors cite additional anecdotal evidence that the Soviet economy is hurting. Last year's collapse of oil prices was a major blow to the Soviets' major foreign-currency earning potential, pushing the Soviets into borrowing heavily from western banks. And the intelligence report cites "poor progress" in the effort to boost the quality and reliability of Soviet machinery.

As former Czech diplomat Milan Svec writes in Foreign Policy, Gorbachev needs to achieve dramatic results in his foreign initiatives "because it will take several years for significant returns from his ambitious, market-oriented economic reforms."

What this means is that the Reagan administration may have a unique opportunity not only to clinch an arms-reduction deal at this week's summit, but also to pave the way for later talks that could open up a whole new era in American-Soviet trade and other economic relationships.

Even if this first stage of the arms control deal is a success, it is by no means guaranteed that economic relations between the two superpowers will blossom. Just as there is bitter right-wing opposition within the Republican Party to Reagan's peace initiative, many conservatives contend that economic issues should not be on the agenda because -- they say -- helping our major adversary would not be in America's best interest. They fear that crucial secret technology will slip behind the Iron Curtain as a consequence of short-sighted efforts to boost American commercial exports.

In any event, opponents of improved economic relationships with the Soviet Union say that a stronger Soviet economy makes for a stronger Soviet military power.

The intelligence report -- a joint effort by the Central Intelligence Agency and the Defense Intelligence Agency -- doesn't grapple with this question directly. But the intelligence community leans toward keeping a distance in economic relations.

"Fundamentally, what they {the Russians} appear to want are agreements that constrain western defense efforts, facilitate Soviet force modernization, and allow them time to complete the U.S.S.R.'s economic development program while staying within the bounds of current defense spending limits," the report said.

A study of these issues by John P. Hardt of the Congressional Research Service makes the contrary argument: A success in Gorbachev's program to modernize the Soviet economy implies a lessening of the priority of military programs, with more emphasis on a "market-simulating economy." Therefore, isn't it in the best interest of the United States to help Gorbachev achieve his goal of making the Soviet system more efficient, as measured by western standards?

Hardt outlines the case for increased American (and western) economic relations with the Soviet Union, always assuming that we achieve the improvements we seek on the political, regional (that means Afghanistan) and human rights fronts.

In other words, changes in trade and tariff rules that would bring Gorbachev the inflow of western management skills and the technology he needs would be dependent on many concrete commitments by Gorbachev, including "tolerance of Jewish culture and an acceptable emigration policy for Soviet Jewry."

If Gorbachev can persuade Reagan that he is moving in those areas, economic assistance from the United States, including management skills and nonmilitary technology, would help him achieve his goals of modernization and restructuring of Soviet society, and thus might assure that he remains in power.

"{But} failure {of the restructuring program} may mean that the Soviet Union enters the next century as a relatively backward, but increasingly truculent, second-class economic power. That would not be in the best interest of the West," according to Hardt.

American businessmen seem eager to cooperate, while reaching for the potential profits in a growing Soviet market. They are convinced that if they stand on the sidelines, they will be yielding the initiative to their European and Japanese competitors, already deeply involved. Obviously, the Russians are keen to pursue joint ventures that will yield not only better products for home consumption, but manufactured goods designed for export sales that will boost the Soviets' hard currency reserves. Internationally minded businessmen insist we can trade with the Russians without giving away military secrets.

The Soviets are keenly interested in joining the World Bank, GATT (the world trade organization) and other international economic institutions for real and prestige reasons -- but so far, they have been rebuffed. What they'd really like, according to Richard Feinberg of the Overseas Development Council, is World Bank assistance in evaluating foreign aid projects. It's possible that could be arranged, through cofinancing, without Soviet membership in the Bretton Woods institutions.

As Hardt suggests, any and all of these economic relationships looked impossible until Gorbachev, glasnost and perestroika came along, and the process of the Reagan-Gorbachev summitry began. "Now the prospects {still} seem challenging, but possible," he says.