The United States is "well ahead" of the Soviet Union in exploiting the military potential of space and has an eight-to-10-year lead in sophisticated warplanes, Gen. Charles A. Gabriel, Air Force chief of staff, said yesterday.

Gabriel, who winds up a four-year tour as the nation's top Air Force officer this month, disputed the recently issued report by Jane's Space Flight Directory, which claimed that the Soviet space program has an "almost frightening" 10-year lead over the United States.

The four-star general also said Air Force and Navy electronic warfare planes were the unsung heroes of the April 15 bombing of Libya. He said the air crews jammed "a dense" array of antiaircraft missiles, as well as the SA5 missile battery at Surt on the Gulf of Sidra.

Gabriel warned against narrowly comparing U.S. and Soviet space programs, stressing that in those areas vital for keeping up with Soviet military activities and fighting a war, "We're well ahead of them."

Seizing the military high ground requires systems for "surveillance, warning, reconnaissance, navigation, weather," Gabriel said. "Saying we're behind in those areas is ridiculous. Surveillance and warning, which stabilizes the whole situation, is the most important thing."

"So you've got a space station up there?" he said of the Soviets. "In terms of usefulness, what is the purpose of being up there?"

Turning to the military impact of the loss of the Challenger space shuttle, Gabriel insisted that "we're not in a crisis situation right now in not being able to launch" the shuttle, because "the stable" of other boosters will keep putting military payloads into space.

"I don't think the two-year hiccup we're going to have waiting for shuttle flights to resume "is going to be a severe setback," he said.

The former fighter pilot brightened in discussing today's Air Force F15 and F16 fighters, declaring that the Soviets are 10 years from having planes to match them -- by which time the United States should have even more advanced fighters in hand.

Today's Air Force planes not only have superior radar, but also can use their computerized systems to outthink and outperform Soviet fighters, Gabriel said. President Reagan's military buildup has boosted maintenance capabilities and enabled modern planes to more than double the ready-to-fight ratios of the 1970s, he said, both in active duty and reserve units.

Instead of the operational readiness rates of about 40 percent for the older and simpler F4 Phantom fighter bombers, Gabriel said, the more sophisticated F15s and F16s are above 80 percent, "unheard of in the history of aviation."

The departing Air Force chief of staff, who said he has not decided what to do in civilian life but will remain in the Washingon area, saw some clouds on the military horizon. His "biggest worry," he said, is that Soviet espionage may cost the United States its technological edge.

The Soviets, he said, are making strides in aircraft with radar that looks down from high altitudes to detect planes flying close to the ground. Accordingly, he said the Air Force must develop a new generation of fighters that can fly above these Soviet search aircraft and knock them down.

In discussing the bombing raid on Libya, Gabriel said the Air Force has evidence that Navy EA6B and Air Force EF111 electronic jamming planes kept many Libyan gunners from firing their missiles.

"That was a very important part" of the raid's success, Gabriel said, because it enabled all but one plane to survive "a dense defense."