Senate Majority Leader Robert C. Byrd (D-W. Va.) said yesterday he will hold the Senate in session past the Oct. 14 adjournment goal if needed to assure final passage of a tax cut.

"We would not adjourn until it's disposed of," Byrd told reporters at his weekly press conference. Byrd also:

Predicted that the final version of the natural gas price bill will go "over the top" and pass with between 52 and 63 votes when it comes up Wednesday.

Eased the way for possible Senate action on legislation giving the states more time to ratify the Equal Rights Amendment. Byrd maneuvered the legislation onto the Senate calendar, which means that opponents can't filibuster the motion to take up the measure. However, once it is taken up, they can filibuster against passage. Byrd said "it is my hope that ERA could be called up," but made clear that measures like the tax bill and remaining appropriations have priority.

Predicted that the Democrats will improve their 62-to-38 Senate margin in the November elections.

Said that as of now he hopes to meet the Oct. 14 adjournment goal and also avoid a post-election session.

Denied delaying a final vote on the public works appropriation bill so that President Carter can veto it after Congress has adjourned. "This majority leader is not going to hold up any measure so the president can pocket veto it."

Byrd said passage of a "moderate" tax cut in the vicinity of $20 billion to $21 billion is "absolutely imperative" and Congress couldn't conceivably go home without doing it.

Even as he spoke, the Senate was giving final congressional clearnce, 47 to 7, to the annual budget resolution. It calls for fiscal 1979 outlays of $487.5 billion and a deficit of $38.8 billion, down from a deficit of about $60 billion projected by the president in January. The resolution called for a tax cut of about $22 billion.

Sen. Edmund S. Muskie (D-Maine). Budget Committee chairman, said the reduced deficit was in part due to deliberate congressional program-cutting and held out hope of balancing the budget early in the 1980s. The House has already cleared in resolution.

Byrd told reports Congress has been giving the president "excellent cooperation," approving his economic stimulus requests, the Panama Canal treaties, the Mideast arms package, civil service revision, repeal of the Turkish arms embargo and part of his energy package.