Senate Republican campaign chairman Bob Packwood (Ore.) yesterday said his party will gain at least two or three Senate seats this year regardless of what happens to the economy or President Reagan's popularity between now and the election.

Packwood, mired in controversy and conflict with the White House for the last two months, made his predictions after the National Republican Senatorial Committee met for the first time since Joseph Coors, a member of Reagan's kitchen cabinet, called for his ouster 10 days ago.

Packwood had invited GOP pollster Robert Teeter and White House political adviser Edward Rollins in to meet with senators. Teeter's polls in states around the country, Packwood said, show that nine of the 10 most vulnerable incumbent senators are Democrats, the same number as a year ago.

"That means we ought to be able to ride out the election no matter what happens," Packwood added. He predicted Republicans would pick up open Senate seats in New Jersey and Virginia and defeat incumbent Democratic Sens. Robert C. Byrd in West Virginia and Quentin N. Burdick in North Dakota.

The meeting was a deliberately low-key one apparently designed to keep any further controversy from arising around Packwood.

The subject of removing him as chairman didn't even come up, according to several participants.

"It was a very cordial session," said Rollins, often a critic of Packwood. Sen. Paul Laxalt (Nev.), Reagan's best friend in the Senate, said the Coors letter could cause damage to Packwood's credibility and support among other senators, "but I don't see that happening yet."

Some Republicans had expressed deep concern about the timing of the briefing. House and Senate Republicans have scheduled their biggest fund-raising dinner of the year, a "Salute to Ronald Reagan," for next Tuesday, and contributions are running 20 to 25 percent behind schedule. So far, $2.3 million has been contributed or pledged to the dinner, compared to $3.5 million a year ago, sources said.

Fund raisers attribute this in part to the Coors letter and controversy around Packwood.

"The concern was that something might leak out of the meeting that could be construed as criticism of President Reagan," said Rep. Guy Vander Jagt (Mich.), chairman of the National Republican Congressional Committee. "You're already talking about a tenuous situation and opportunity for misinterpretation is great."

Packwood has been in hot water with the White House since March 1, when he told an Associated Press reporter that Reagan was harming the GOP among blacks, Hispanics, women and blue-collar workers.

The White House retaliated by asking that a fund-raising letter prominently picturing Packwood be withdrawn from the mails because it contained an unauthorized presidential signature. The Senate committee then destroyed 8 million copies of the letter, produced at a cost of $2 million.

On April 15, Coors, an ultraconservative brewery owner, sent a letter to 2,500 Republican contributors saying, "We must withhold financial support from the Senate campaign committee until Packwood is removed."

The letter was also signed by former White House political adviser Lyn Nofziger, who Packwood claims originally approved the use of Reagan's signature on the committee's fund-raising letter last May.

The Coors letter angered many Senate Republicans, who regarded it as an intrusion into their affairs. "It was a lousy thing to do," said Sen. Dan Quayle (Ind.). "They're doing a disservice by trying to foster division. It's silly and it doesn't benefit anyone."

Vander Jagt and others indicated that the Packwood controversy has been a key factor in handicapping their fund raising. The situation has become so sensitive that organizers decided to abandon plans for a program that was described as a "light-hearted spoof" on the party.

"I'm convinced if Bob Packwood were not chairman, we could raise another $1 million this week," said one source.