Soviet Foreign Minister Andrei Gromyko held out the hope tonight of a Soviet-American summit once a breakthrough is achieved on a new strategic arms limitation agreement. "It can be said the two powers have now stepped on the road which leads to agreement," Gromyko said.

In a television interview, Gromyko reaffirmed the generally positive picture present here in recent days of Gromyko's talks in the United States with President Carter ad Secretary of State Cyrus Vance.

A meeting between Carter and Soviet President Leonid Brezhnev would be beneficial "for the cause of peace" and "would be a big step forward in the development of Soviet-American relations, Gromyko said in what appeared to be a display of new Kremlin interest in such a meeting.

Gromyko made the assertion during a filmed interview with a Soviet broadcaster in New York before the foreign minister left there for Moscow today. The interview was broadcast tonight and a text of his remarks released by Tass, the official government nes agency.

Describing his talks in the White House with Carter earlier this week, Gromyko said: "The president did not conceal that he wants to meet Leonid Brezhnev. By the way, he also spoke about this before. So it would be good if such a meeting was duly prepared and actually took place. This would be a big step forward in the development of Soviet-American relations and would be one of the great importance for the cause of peace in general."

Gromyko also reiterated for his Soviet audience that there has been progress in the Strategic Arms Limitation Talks (SALT). The present agreement, signed in 1972, expired Oct. 3. Both countried pledged, a week ago to refrain from adding new weaponry to their nuclear arsenals once, the present agreement lapses. Gromyko and Vance also pledged to press ahead toward a new SALT accord.

Gromyko said the two sides were brought somewhat closer . . . The situation is better today than it was yesterday. It may be said the two powers have now stepped on the road which leads to agreement.

"But it cannot be said yet that all questions have been decided. Some questions still remain, but I would put them in second place. Some of them and even, perhaps, most of them can be finished off by the delegations of the two countries in Geneva. As is known, the main issues are decided at a different political level and some progress has been made on the key issues."

He thus seemed to be hinting that the "different political level" could be a summit. In the past, Western diplomatic sources here have suggested that the Soviets are eager to portray Carter as being the one seeking a summit, which in diplomatic terms could place him in a subtly different and weaker, position as the "asker" who must agree to terms before he can get what he wants.

Gromyko also painted a picture for his viewers of the U.S. political scene remarkably more benign that presented almost daily by the government-controlled media. The ollficial press has cast Carter and his administration as coming under the influence of powerful conservatives who profit in various ways from an escalating arms race.

"The political situation in the U.S. (is) noted for the its complexity and the presence of many different currents, as in oceans.