Egypt is approaching the Camp David summit conference sustained by a conviction that President Carter is prepared to take strong action to break the Middle East impasse.

Members of the Egyptian delegation say they cannot believe that Carter issued his invitation in a void. The American president must know, they say, that U.S. interests in the Middle East and Africa may depend on the outcome of the meeting that starts Wednesday and so he must have something to offer that would show determination to put stated U.S. policies into action.

That hope has not dispelled a widespread sense of gloom and forboding that Egyptian peace initiative may be nearing a dead end and that disastrous consequences could follow.

The Egyptian news media have been talking of the summit in apocalptic terms, describing it as "the last chance" for peace. Cairo radio said the "the tripartite summit will show once and for all whether the U.S. is capable of fulfilling its responsibilities."

Informed Egyptian officials say the situation is not quite so black-and-white. The stakes at Camp David are so high, they argue, that it is unlikely the conference would end with an admission of failure. It would be camouflaged so as to postpone the crisis that such an acknowledgment might bring, they say.

"The absolute worst case," one informed Foreign Ministry official said "would be that U.S. pressure on both Egypt and Israel would force us to find some framework to keep the talks going. It would postpone the open breakdown that would send the issue back to the United Nations, which nobody wants."

"The very least that can happen," a member of the Egyptian delegation said "is that the conference will postpone our counterinitiative."

He was vague about the meaning of that phrase, but the Egyptians have been dropping hints that failure at Camp David would force this country to take a new tack. Military action appears to be beyond Egypt's capability, even in concert with Syria, and is certainly beyond its desire. But there is talk of political moves, such as an approach to Saudi Arabia, for an attempt at restoring Arab unity and giving up the effort to cajole the Israelis into giving up the lands they occupied in 1967.

Going into Camp David, however, the Egyptians argue that it is not they but the Americans who will determine the course of events. Egypt's reliance on a U.S. solution, should direct talks with Israel fail, has been building ever since the deadlock at the meeting between Israeli Prime Minister Menachem Begin and Egyptian President Anwar Sadat last Christmas.

In the absence of any evidence that Egypt or these talks that revived Egypt's flagging hopes for Israel is going to Camp David prepared to offer substantial changes in its demands, the Americans hold the key to the outcome, the Egyptians believe. It was the U.S. promise to act as a "full partner" in these talks that revived Egypt's flagging hopes for peace, because the Egyptians believe that the American version of a settlement is much closer to their's than to that of the Israelis.

The Egyptian people, beset by poverty, overcrowding, deteriorating public services, political restlessness and of their territory occupied by an enemy for more than a decade, have clung since last November to the promise of peace that Sadat raised with his trip to Jerusalem.

Many observers here believe that a wave of domestic turbulence might follow an official admission that their hope was not to be fulfilled.

Beyond Egypt's borders, King Hussein of Jordan is not alone in his belief, expressed on U.S. television, that failure at Camp David would bring "upheavals in the Arab world."

There is a widespread feeling here and in other Arab capitals that something dramatic and perhaps uncontrollable would happen if the November anniversary of Sadat's trip to Jerusalem came around with no sign of progress.

Sadat and his top officials insist, however, that the need for a settlement and the urgency of peace will not induce Egypt to offer substantive changes in its negotiating position.

"The Arabs have given more than what is required in their search for peace and were flexible to an extreme," the semi-officials newspaper Al Ahram said. "It is high time that the other side offer something for the sake of peace for itself and for the entire world. Egypt could not go beyond this and peace will never be achieved at the expense of land or national sovereignty."

Although the formulations vary slightly from speech to editorial, Egypt's stance remains essentially what it has been for months.

It is that if Israel will commit itself in principle to an eventual withdrawal from all the occupied territories, with only minor border rectifications, peace can be had for the asking.

Egypt, its own negotiators say, is prepared to accept almost any time-table, any formula for interim control, any security guarantee the Israelis want once it is understood the flag of Israel must eventually be hauled down over those lands and Arab sovereignty restored.

If Israel holds out for a territorial compromise on the West Bank of the Jordan River, Egyptian negotiators say, they will counter with the argument that they have no legal standing to bargain over non-Egyptian land and only Jordan or the Palestinians can conduct such negotiations.

Israel can only entice Jordan into the negotiations, the Egyptians say, by making an advance commitment to an eventual pullout, leaving the schedule and the terms to be worked out.

Like the Americans, the Egyptians say peace can come only if there is a resolution of the Palestinian question, but Egypt has made clear for months that its definition of an acceptable formula on that issue is considerably softer than a demand for an independent Palestinian state run by the Palestine Liberation Organization.

Egypt would settle for a temporary restoration of Jordanian control over the West Bank, and Egyptian control over the Gaza Strip, with the Palestinians "to determine their own future" after five years.

For Egypt, the danger in this position lies in accepting a settlement that appears to the rest of the Arabs to be too soft.

The Egyptians insist that they cannot negotiate a bilateral deal or a separate peace that would take them out of the struggle for the rights of the Palestinians. The Egyptians doubt they can get a West Bank deal that would satisfy the PLO or the Syrians, but they must get at least enough of what one Egyptian official calls a "figleaf" to make it acceptable to Saudi Arabia and Jordan.

At a recent meeting in Saudi Arabia, Crown Prince Fahd is reported to have given assurances to PLO leader Yasser Arafat that Egypt would not make a bilateral settlement. Those reports have the ring of truth because Sadat cannot afford, economically or politically, to arouse the enmity of Saudi Arabia.

Egyptian commentators say there is nothing in Israel's stated positions to make it seem likely, or even possible, that a West Bank deal can be concluded.But some Egyptians say they detect signs of flexibility among some Israelis that could justify a continuation of the negotiations if this flexibility is exhibited at Camp Davd.

It is some nugget such as this, rather than a comprehensive breakthrough, that Egypt is hoping for at the summit meeting - a lot less than seemed available during the heady days of last winter, but a lot more than was on the horizon before the summit was scheduled.