The Soviet government tonight hailed the new strategic arms limitation treaty as a "triumph of patience and endurance, a triumph of reason that should improve overall Soviet-American relations.

In its first substantive comment on the pact, the government's evening newspaper Izvestia declared, "the treaty will put a definite obstacle in the path of further stockpiling of nuclear weapons by the superpowers.

Izvestia asserted that once the treaty is in force, work will start on the SALT III agreement," which shape up as a far more complicated and far-reaching arms control negotiation than SALT II.

The authoritative statement was awaited eagerly here and in Washington since Secretary of State Cyrus Vance announced the treaty at the White House Wednesday. It is perceived here as strongly indicating the Soviets will take a generally positive tone in their words - and perhaps deeds - Before the June summit meeting of Leonid Brezhev and President Carter in Vienna.

SALT II represents a realization by the two powers of the cardinal fact of today that there is no reasonable alternative to detente," wrote senior Izvestia commentator Stanislav Kondrashov in an article that doubtlessly was reviewed carefully by the Kremlin's highest levels.

The article also seems to indicate Soviet intentions in the crucial months after the summit, when the treaty faces a stiff fight for ratification in the U.S. Senate.

The commentary acknowledges that fight, making clear how serious the Soviets view it by declaring, "On Capitol Hill, there will be a very dramatic battle, one of the more serious in American history."

It added that "notwithstanding the importance of the treaty itself, it will not remain the only impetus to be imparied to detente, to the cause of improving Soviet-American relations . . . There is also hope that other negotiations will be activited, having to do with limiting the arms race. Finally, creating a more favorable climate the SALT II treaty may help tackle other problems of Soviet-American relations and international life." He said a similar assessment revails in the U.S. administration.

But Izvestia implied that Soviets are aware that Brezhnev's personal prestige and that of his government soon will ride on forces beyond Kremlin control or influence.

"At the present encouraging moment, one cannot fail to mention one circumstance which casts its shadow . . ." he wrote. While the treaty has been practically agreed on and prepared for signature by the governments, there is still no clarity with regard to its ratification in the U.S. Senate in which approval will require a two-thirds majority."

The article reiterates the Soviet position that the treaty is the cornerstone of bilateral detente.

"For many years of talks on SALT II, their state became a main barometer defining weather in Soviet-American relations," it says."The talks themselves have become a principal element of these relations. So now this barometer indicates for improvement of the wealther, and it is not mere chance that the news about the Vienna meeting is being welcomed in the entire world. The treaty itself will have great significance."

The article, headlined "Long-Avaited News," and played on page four of Izvestia, suggests an unmistakable shift of emphasis by the leadership from six months ago, when Soviet Premier Alexei Kosygin told a group of visiting U.S. senators that he knew more than they about how the Senate worked.

The article does not mention the question of Brezhnev's poor health - it would be surprising if it did. And it reflects the consistent maneuvering here recently to remove the Kremlin from any responsibility for the possible failure of ratification. It says the talks, stretching more than six years were a "marathon," created in parts by "obstacles . . . which it is worthwhile to mention were not created by the Soviet side."

Later, it asserts, "It is not a secret" that the need for the White House to look "over its shoulder to Capitol Hill" extended the marathon. It classes the opponents as "direct agents of the military-industrial complex, anti-Sovietists, and lobbyists of various colors . . . Those senators who have not yet defined their attitudes to the treaty will be subject to the most sensitive working over."