After three seasons with scant reward for an estimated $1 billion investment in the sport, the Japanese car giant is second in the championship after three races and two successive podiums.
Ferrari, champions for the last six years, are meanwhile struggling in sixth position.
"It's exactly what Formula One needed," said Gascoyne after Italian Jarno Trulli finished second to Renault's championship leader Fernando Alonso in Bahrain on Sunday to follow up his second place in Malaysia two weeks before.
"Formula One's always been cyclical, teams get it right and then they drop off.
"I think you are just seeing the result of that.
"There were teams that were coming up, Toyota have probably come from nowhere but Renault was building up, and you've just seen the results of that."
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"We were undoubtedly helped by the regulation change, there's no doubt about that. It levelled the playing field so that instead of having to catch up, everyone was starting from the same level," added the Briton.
"And we did as good a job as the top teams.
"If the regulations hadn't changed, the top teams would have been ahead. We'd have moved above some people but not to the level we are."
Engine, tyre and aerodynamic regulations have changed this year, pushed through by the sport's world governing body on safety grounds to prevent cornering speeds from becoming dangerously fast.
Engines must now last for two successive races, tyres for qualifying and the race while the aerodynamic changes have stripped the cars of much of their downforce.
Toyota, with Renault and Ferrari, are both chassis and engine makers unlike other teams who are either partners or clients of major manufacturers.
Gascoyne said Ferrari, whose new car looked quick but failed to score points on a troubled race debut at the weekend, could not be written off but their dominance had ended.
"They've got a lot of work to do," he said.
"It's good for Formula One. They will do it and be very competitive this year, there's no doubt. They will win races and they'll be strong. But they won't be dominant."