President Reagan's national security affairs adviser, Robert C. McFarlane, said tonight that "the prospects are good" for a superpower arms-control agreement and predicted that Reagan and Soviet leader Mikhail Gorbachev may agree to a "commitment" to reduce offensive nuclear weapons when they meet in Geneva this month.

In a speech to the American Swiss Association on the eve of his departure for Moscow with Secretary of State George P. Shultz, McFarlane said the Nov. 19-20 summit is not likely to produce a "signed, sealed and delivered agreement" on nuclear weapons. But he said "it's a good moment" for progress because of developments in the U.S.-Soviet military balance, economic pressures on the Soviets and "creative leaders on both sides."

McFarlane added that Reagan is "optimistic" about some kind of agreement with the Soviets to limit nuclear weapons in the months ahead.

"For the first time we are entering negotiations where each side has both incentives and something to bargain with and about," McFarlane said. He said the Soviets face a resurgence in U.S. military strength and also may want to shift resources from defense to their economy, although he noted that "seldom have Soviet leaders been moved to go in that direction."

McFarlane's comment about the prospects for an arms accord with the Soviets came on the day that the United States presented a proposal to Soviet negotiators in Geneva calling for deep cuts in offensive nuclear arsenals.

McFarlane emphasized in his address here tonight that Reagan intends to insist on direct linkage between Soviet behavior in regional conflicts in Central America, Asia and Africa and negotiations on reducing nuclear weapons. "You cannot separate regional problems or human rights from arms control," he said.

Echoing the president's address to the United Nations last week, McFarlane cited "linkage" between the 1979 Soviet invasion of Afghanistan and the withdrawal from the Senate of the SALT II treaty.

"President Reagan has said he wants a 'fresh start' in relations between our nation and the Soviet Union," McFarlane said. "This means improvement in many different ways . . . . We cannot expect a fundamental or a lasting change by addressing just one area, such as arms control."

McFarlane suggested that Soviet involvement in Third World conflicts has become a growing burden that could propel Gorbachev to reach some accommodation with Reagan, who last week proposed a regional peace initiative.