Beirut — Lebanese President Amin Gemayel is quietly maneuvering for autocratic powers to rule - and reshape - his troubled country.
By gaining these powers, Mr. Gemayel would be able to remake Lebanon's main institutions and its ''confessional'' system of government (which guarantees ruling leadership posts for major religious factions). He could act virtually unchecked in consolidating rightist Maronite Christian dominance of Lebanon and in making peace with Israel.
Mr. Gemayel will achieve these powers easily if parliament agrees on Nov. 8 to give the Council of Ministers (the 10-member cabinet) power to rule by decree for the next eight months. If that fails, diplomats say, Gemayel eventually may choose to dissolve the parliament and rule by decree anyway.
With this power, Mr. Gemayel may well restructure the parliament's electoral law. The eight-month special powers mandate would end just as parliament's current term ends on June 30, 1983. Thus a new parliament could be elected on a basis devised by Mr. Gemayel in the interim.
President Gemayel also could alter Lebanon's army, taxation, and civil service laws in ways that would change the sectarian and ethnic balances in the country's most important institutions.
Such changes, diplomats note, might make Lebanon less prone to anarchy. After seven years of civil strife these changes might be welcome even by those who stand to lose influence. But overall, the maneuvers seem designed to establish the Maronite right as the dominant class in Lebanon politically and militarily, to go along with existing Maronite economic dominance.
A diplomat who is versed in the Lebanese Constitution and who has studied Mr. Gemayel's gambit believes the current situation is ''almost a formula for dictatorship.''
Another diplomat notes that Mr. Gemayel has ''definite autocratic tendencies.''
That view, however, is seen as overly alarmist by many Lebanese political analysts - including those in the Sunni Muslim and leftist communities of west Beirut, which would have a diminished voice in the government under the diplomats' scenerio. These experts believe Lebanese Prime Minister Shafik Wazzan , a Sunni, would balance Mr. Gemayel and look out for non-Maronite interests if the cabinet receives such sweeping powers. West Beirut leaders also say they are confident that Mr. Gemayel, who has actively courted their support, will not disenfranchise them.
Although there is parliamentary opposition to giving the cabinet a broad mandate, some form of authorization is likely. The objections center mainly on the cabinet's authority to change the system for electing the parliament.
''I don't think Amin will run away with the country,'' a leading Lebanese editor says. ''Wazzan is there to ensure that.''
But two diplomats point out that President Gemayel - not Prime Minister Wazzan - chairs the Council of Ministers. While the media have portrayed the move for special powers as Mr. Wazzan's request (he delivered the request to parliament last week), it is Gemayel who would receive the power.
''The Lebanese system of government is very clever,'' one diplomat says. ''It gives the president all the power but it makes the prime minister responsible for every problem. The president is virtually immune.''
Under the previous administration of Elias Sarkis, Prime Minister Selim Hoss twice was granted special powers, each time for six months. Mr. Wazzan last week argued that conditions in the country ''are more critical and serious'' than they were during the Sarkis-Hoss days.
But Gemayel is a stronger leader than was Sarkis - and, following Israel's invasion last summer, the Maronite community is in a much stronger position than it was in 1976.
Nevertheless, some form of special powers - perhaps restricted only to specified areas such as defense, security, justice, reconstruction - are needed, say supporters of the move, to give the government a free hand to secure the withdrawal of foreign forces and re-establishment of state authority in all Lebanese territory. This seemed particularly urgent given sectarian clashes last week.
Lebanon's south is occupied by Israel, its Bekaa Valley by Syria and the Palestine Liberation Organization (PLO), while the coastal north is under de facto control of the Maronite Phalange militia. These, say proponents, are where authoritarian powers may be most necessary.
A government committee Nov. 8 is to begin talks with Israel on guaranteeing a PLO-free south in exchange for Israeli withdrawal. Israel, however, insists that such a guarantee would be possible only if Syria and the PLO pull out of Lebanon first and if Lebanon signs a peace treaty with Israel.
Meanwhile, Gemayel wants to bring the Army's strength up to 60,000 from 22, 000 to enforce sovereignty over all the country. To do so quickly he may turn the 20,000-man Phalange into a national guard or merge it with the Army.
Neither guarantees to Israel, nor legitimizing the Phalange, will be popular with Lebanese Muslims and leftists. But if he acts alone, Gemayel may circumvent objections.