Israeli Foreign Minister Moshe Dayan, citing "good progress" in the Egyptian-Israeli peace talks, said yesterday that the outcome of the negotiations could be determined at a New York meeting today between Prime Minister Menachem Begin and Secretary of State Cyrus R. Vance.

After a meeting with Vance, Dayan was asked by reporters if the three-week-old talks on a peace treaty are nearing completion. He answered: "Well, almost."

However, Dayan added that neither the Israeli nor the Egyptian negotiating team in the U.S.-mediated talks has sufficient bargaining authority to overcome certain remaining obstacles, and both would require more flexible mandates from their government.

For that reason, Dayan said, Vance's meeting with Begin could be especially important. He noted, "Many points that we don't have a mandate to agree about or even discuss would come up between the secretary and the prime minister."

The meeting with Begin, who arrived in New York yesterday to begin a private U.S. and Canadian visit, has triggered growing seculation about whether the Carter administration is giving him a calculated cold-shoulder treatment.

Although President Carter also will be in New York today, the White House has insisted there will be no meeting between the two leaders. That has been interpreted widely as a sign of the administration's displeasure over Israel's controversial decision last week to expand its settlements on the West Bank of the Jordan River.

In the face of this growing speculation, both White House press secretary Jody Powell and the State Department spokesman, Hodding Carter, denied yesterday that the administration was trying to administer a snub to Begin.

"There has been no request for a meeting." Carter said. "There has been no turndown. The issue has not arisen. There has been nothing in the works on either side."

Begin, on his arrival in New York, denied that he was disappointed at not being able to see Carter. He said: "I don't think President Carter would snub me. Why should he? We have had very cordial relations within the past few days and I know our efforts for peace are going well."

But despite the denials, the administration is known to be concerned about the issue of Israel's West Bank settlements, and it is expected to play a big part in the talks between Begin and Vance.

All sides reportedly are trying hard not to let the settlements issue impede the drive toward an Egyptian-Israeli peace treaty. However, the administration, in looking ahead toward the next stage of the effort to achieve a comprehensive Middel East peace, is fearful that the Israeli action will be seen in the Arab world as an effort to strengthen Israel's claims to the West Bank, and make such key Arab states as Jordan and Saudi Arabia reluctant to join the peacemaking process.

Another matter expected to figure prominently in the Vance-Begin talks involves Israel's bid for substantial U.S. financial aid to offset the costs of Israeli withdrawal from the Sinai peninsula after a peace accord with Egypt is concluded. Some estimates of what Israel reportedly is asking run as high as $4.5 billion.

Since this is essentially a matter between Israel and the United States, the question of compensation hasn't been addressed in the three-way talks here. But there has been speculation that Begin might demand a firm U.S. commitment on aid as a condition for Israeli agreement to a peace treaty.

The tug of war over financial assistance was underscored earlier this week when the administration postponed a planned visit by Assistant Scretary of Defense David E. McGiffert to Israel. He was supposed to discuss the costs of the Israeli military redeployment from the Sinai to Israeli territory.

The administration has refused to discuss its reasons for deferring McGiffert's trip. However, it is known that Washington, despite its denials of a linkage, believes that progress toward resolving the question of financial aid should depend on progress toward reaching a treaty.

The United States so far has made no formal commitments about how much it is willing to pay Israel; the feeling in the administration is that for McGiffert to go to Israel now would constitute a tacit acknowledgment that some kind of commitment has been made.

Before doing that, the administration wants to see further movement toward a treaty agreement. But if the anticipated progress does become evident in the peace talks, the expectation is that the McGiffert mission will be quickly rescheduled - probably shortly after McGiffert's scheduled Nov. 13 return from a Far Eastern trip.

Begin, on his arrival, spoke in upbeat terms about the outlook for the negotiations. He said: "There are still problems and there are a number of good chance we shall overcome them and have a peace treaty."