The Egyptian government seems increasingly confident that its Arab foes are losing momentum in their drive to isolate President Anwar Sadat and punish him for making peace with Israel.

This spreading conviction, reinforced by Arab world developments over the last few weeks, has strengthened Egyptian resolve to persevere in Palestinian autonomy talks with Israel despite the lack of progress registered so far. Observers predict it also will encourage Sadat to proceed with improving relations with Israel even in the face of prolonged difficulties in the autonomy talks.

As a demonstration, they point to this week's summit conference between Sadat and Israeli Prime Minister Menachem Begin in Haifa. The two leaders announced progress on a Sinai observer force and sales of Egyptian oil to Israel, but once again agreed only to disagree on Palestinian autonomy and sovereignty over Jerusalem.

The lack of movement on these key issues seemed all the more apparent because Sadat had underlined their importance and his determination to win concessions on them only two days before setting sail for Haifa on the presidential yacht.

It is precisely concern over these demands shared across the Arab world that animates the alliance of Arabs ranged against Sadat and his March 26 peace treaty with Israel. The alliance, however, seems to officials here in Cairo to be fraying around the edges because of discord among its members.

The most recent and obvious sign came early this week with Sadat's unexpected announcement that he is ready to give military aid to Morocco's King Hassan II for his war against Polisario guerrillas in the Sahara.

Hassan's government responded two days later with a cautious but warm statement of thanks to Sadat and the "fraternal Egyptian people." Left unsaid was whether Hassan had actually requested arms from Sadat and whether Sadat already was sending them.

Nevertheless, the principle had been established: Sadat offered aid and Hassan welcomed the offer. Egyptian Foreign Ministry officials were quick to suggest a "look at the implications," meaning Hassan was weakening in his opposition to the peace treaty or at least was breaking ranks with the Arabs boycotting Sadat because of it.

Hassan traditionally has been a friend of Egypt and the West, observers noted, and originally backed Sadat's precedent-shattering trip to Jerusalem in November 1977. He thus was a soft spot in the Arab boycott from the beginning, all the more so because of his isolation in the fight against Polisario irregulars seeking an independent Sahara state.

But another more decisive sign of weakness in the forces ranged against Egypt, which Sadat himself is fond of pointing out, is the apparent halt in unification and cooperation talks between Iraq and Syria. In addition each of the two nations has troubles of its own, with a clash for power in Iraq and renewed sectaran strife in Syria.

More important for Egypt, the new power axis between Baghdad and Damascus, which had the potential for decisive change in the Arab world, appears for the time being to have split once again in mutual suspicion. After reports that Syria was involved in a failed coup plot against President Saddam Hussein of Iraq, President Hafez Assad of Syria acknowledged recently that the unification plans have stalled.

With the two Baathist neighbors once again divided, or at least distracted, the power center around which opposition to Egypt revolved has become less well defined and thus less effective, Egyptian officials say.

In a reflection of this official thinking, the guided Cairo press has been making front-page headlines this week out of the recent flareup between Sunni Moslems and members of Assad's Alawite Moslem minority in the Syrian port of Latakia.

Sadat also referred to the Egyptian impression of discomfiture among his enemies in a conversation Wednesday in Haifa with Israeli newspaper editors, where he was reported to have said:

"In Iraq, the president was overthrown. In Syria, the situation is getting worse, especially after the Lebanese fiasco. In Morocco, in Algeria, in Libya, in the Gulf countries, the situation is changing, and even in Saudi Arabia, people are talking about changes at the top."

In fact, the all-important Saudi attitude remains for Egyptians the most difficult to judge. One Foreign Ministry officials suggested that Hassan's friendly response to the offer of Egyptian arms aid was a sign that Saudi irritation at Sadat was declining. Hassan would do nothing to break Arab ranks, his reasoning went, without first checking with Saudi Arabia.

But other Egyptians pointed to the visit to Rabat this week by Prince Abdullah, deputy prime minister and head of the Saudi National Guard, as an indication the Saudi rulers were trying to prevent Hassan from leaving the fold. Abdullah, they pointed out, is considered among those within the Saudi royal family most strongly opposed to the Camp David accords.