Negotiators for film and television directors have reached a settlement with major motion picture and TV producers on the crucial issue of sharing new pay television revenues, it was learned yesterday.

The settlement, which still has some details to be resolved, is expected to prevent a walkout by the 6,300 members of the Directors Guild of America when their contract expires next Wednesday.

A strike by directors would curtail virtually all film and TV production.

The settlement allows producers to show programs made for pay TV for one day on cable systems with fewer than 5 million subscribers without triggering residual payments to directors.

Once the subscriber level of 5 million is reached, directors would receive 2 percent of all monies taken in by the producers after they recover production costs.

The 5 million-subscriber level would remain constant for the first two years of the three-year contract, but would drop to 3 million subscribers in the final year.

Should the directors ratify the new contract, it would leave striking writers alone on the picket lines. Writers vowed yesterday at a mass picketing at 20th Century-Fox film studios to continue their strike until they reach their own settlement.

Frank Pierson, vice president of the 8,500-member Writers Guild of America, was one of almost 1,000 striking writers picketing outside the studio lot of 20th Century-Fox here yesterday, as the writers' strike neared its third month.

"We pushed open the door, and the directors walked right through it," said Pierson, referring to the formula first proposed by the writers to allow producers to recover production costs. That formula is now part of the directors' settlement.

Directors Guild officers will meet with members Sunday. If they recommend ratification, members will vote Tuesday in Los Angeles and Wednesday in New York.