The Warner Theatre said yesterday it had sold 500 of its 2,000 reserved seats for the closed circuit telecast on Saturday night of the Pipino Cuevas-Tommy Hearns welterweight championship bout from Detroit.

Fewer than 8,000 tickets have been sold for the World Boxing Association title fight in the 20,000-seat Joe Louis Arena in Detroit and nearly half of the closed-circuit telecasts throughout the country have been canceled, leaving about 80 sites in the Far West and Southwest, where Cuevas, of Mexico, is popular.

Dave Jacobs, Sugar Ray Leonard's trainer, is predicting a "dynamite" fight, with Cuevas losing his championship. Jacobs asserts that Hearns is "tougher than Roberto Duran," who took Leonard's World Boxing Council title on June 20.

Jacobs worked in the corner of Hearns in 1977, when he was an amateur, and he brought Hearns here to spar with Leonard, who was preparing to fight Hector (Chino) Diaz at the D.C. Armory-Starplex.Leonard knocked out Diaz after 2 minutes 20 seconds of the second round.

"Tommy was here in Washington for a week and he looked very good against Ray. They were dynamite workouts; they would have been worth $5 to see," Jacobs recalled.

Others said at the time that Leonard had no trouble handling Hearns as a sparring partner, and afterward Hearns wasn't eager to fight the former Olympic champion.

"That's not true," Jacobs said. "I didn't want to see them fight when they were both unbeaten unless it couldn't be avoided, because it would have been a shame then for one of them to have to lose, and they were good friends. I thought Tommy would fight Ray then anyway, to get big money."

Asked how Leonard would do against Hearns now, Jacobs replied, "Very well. Over 15 rounds Ray would beat Tommy, though Hearns might give him trouble for a few rounds. Ray would do better than Cuevas will against Hearns; Ray would outsmart Tommy with his boxing ability, like Muhammad Ali outsmarted a bigger George Foreman."

Hearns is a rare combination of a tall (6-foot-2 1/2), skinny guy being a good puncher (with 26 knockouts while going unbeaten in 28 bouts) . . . like Bob Foster, Sandy Saddler, old-timer Honeyboy Finnegan, and Gene Smith, the onetime Washington featherweight.

"With his height, reach and punch, Hearns is tougher than Duran. He could step up into the junior middleweight division. Cuevas taking on Hearns is like light heavyweight champion Dick Tiger taking on Foster. Tiger was on his last legs and wanted to make big money. Foster destroyed him. (Champion Cuevas will receive $1.5 million on Saturday; challenger Hearns $500,000).

"I see a dynamite fight for 10 rounds between Hearns and Cuevas, and then Hearns will stop him.

"Sugar Ray and I saw Cuevas knock out Harold Volbrecht in Houston. Cuevas is always in front of you. He can hit hard, but he can be hit easily. He suffered a cut eye while winning (it canceled a bout with Leonard scheduled for May 20). I believe in the depth of my heart that Hearns will beat Cuevas.

"I think Ray would do better against Cuevas than against Hearns. He would outsmart Cuevas. You don't take chances against Hearns, with his height and punch."

Asked whether Cuevas could win, Jacobs said, "No way. Saturday night will tell just how good Tommy is. The day will come when they will try to match Ray with Hearns, but Ray won't fight any of the top four welterweights -- Wilfred Benitez, Cuevas, Hearns, or Roberto -- until Ray has two tuneup bouts. He won't fight Duran first.

"Ray needs to get his timing back, and his mind back together, because if he lost one more bout, psychologically it might do something to him."