CIA Director William J. Casey appeared to be gaining yesterday in his fight to keep his job as he steered his way through Senate offices with an increasing air of confidence.

Casey will testify in closed session before the Senate Intelligence Committee today, but the allegations presented to the committee in an executive session yesterday morning evidently contained no surprises.

Sen. Richard J. LUGAR (R-Ind.) said that the briefing, "as far as I'm concerned, laid to rest all of the previous questions about Mr. Casey's business deals."

Lugar suggested that the CIA director's appearance today would be somewhat anticlimactic, "just an opportunity for Mr. Casey to state on the record his defense."

Two other Senate committee members also indicated, after visits from Casey yesterday afternoon, that they saw no reason at this point for him to resign.

"To this point, they haven't laid a glove on him," Sen. Lloyd Bentsen (D-Tex.) said of the preliminary report the committee's staff has compiled since the inquiry into Casey's activities began July 17.

"I have yet to hear or see any credible evidence that would lead me to believe Mr. Casey should resign," Bentsen declared.

The investigation, primarily into Casey's business activities, was triggered by the quick resignation two weeks ago of his chief of covert operations, Max Hugel, following disclosure of alleged financial improprieties on Hugel's part.

The CIA director denied any misconduct, but seemed to be on the verge of a forced depature last week when Senate Intelligence Committee Chairman Barry Goldwater (R-Ariz.) said publicly that he thought the poor judgment Casey showed in having insisted on Hugel's appointment was cause enough for him to resign.

Most other committee members balked at that standard and said they would wait to see if the committee's investigation turned up proof of previously unsuspected misconduct in Casey's long private and public careers.

The CIA director told reporters yesterday he was sure nothing would turn up. For Casey, it was a day full of cliches and good cheer. He said, "Hundreds of reporters have been calling my friends and [former] clients" in recent days, but to no avail.

"The bottom of the barrel has been scraped," Casey declared in a crowded hallway press conference outside Bentsen's office. "There's nothing there."

Was he concerned about any of the allegations that he might be questioned about in his forthcoming appearance before the Senate Intellegence Committee?

"You know, fellas, I'm not concerned about anything," he replied. "My life is an open book. I'm ready to discuss any phase of it -- but not here, not at this time."

From there, he hurried upstairs for what proved to be a much longer session with Sen. Patrick J. Leahy (D-Vt.). Last week Leahy had reportedly been planning to call for Casey's resignation himself, but yesterday afternoon he said he would do so only if "allegations of wrongdoing" were made and sustained.

Leahy also told reporters that there were not even any charges currently under investigation concerning Casey that would justify his ouster, even if confirmed.

"Maybe it was bad judgment, but I just don't believe they could turn me out for this," Casey himself was quoted as telling Washington Star columnist Mary McGrory about the Hugel appointment. "The only thing that could get me was if I can't deal with the committee after this."

Goldwater, meanwhile, was holding his fire. Asked at a hectic conference in the din of the tourist-filled Capitol crypt whether he continues to feel that Casey should resign, he simply took note of the fact that President Reagan is still backing the CIA director.