Gene Upshaw, 16 years a player in the National Football League and long an officer in the NFL Players Association, succeeded Ed Garvey yesterday as executive director of the union and vowed to keep the pressure on the league.

Upshaw, NFLPA president during the sometimes-bitter 57-day strike last season, was asked whether moving up to the top job would require him to soften his militant image to facilitate dealing with the league's owners. His response: "I'm 6-foot-6, 250 pounds, big, strong and black. My image portrays that."

Upshaw said the key issues now facing the union are regulating agents who represent players, enforcing the collective bargaining agreement that ended the strike and closing union ranks. And organizing players in the new U.S. Football League . . .

Tickets for the Washington Redskins' preseason games here against the Cincinnati Bengals (Aug. 12) and the Miami Dolphins (Aug. 19) will go on sale today at 9 a.m. at the RFK Stadium ticket office. The Redskins, WMAL Radio and area McDonalds are sponsoring the games, benefiting Ronald McDonald House . . .

Tampa Bay Buccaneers offensive tackle Dave Reavis has been praised for helping several of the 141 passengers on United's flight 200 escape when an engine on the aircraft caught fire Saturday at O'Hare International. Nineteen were injured, most slightly, but the 6-foot-5, 265-pound Reavis was "fantastic," said Judith Papen, St. Petersburg, Fla., nurse.

He calmed other passengers, "ripped open the exit door" and led her and other passengers onto the wing, then jumped to the ground and tried to catch others who leaped, she said . . .