The line of Pacioretty, Stastny and Stone combined for 12 points in Game 3 and has 22 in the series.
"Tonight, just so happened that we were the offensive difference," said Pacioretty, who had an assist. "It's not always going to be the case. You don't always prepare for that. Tonight, that just happened to be the case."
Labanc scored at 15:26 to make it 2-1. Vegas coach Gerard Gallant challenged for goaltender interference by Labanc, but the goal was upheld after video review.
Stastny scored twice in the second. His first goal came 21 seconds into the period to make it 3-1. He scored a power-play goal at 16:04 for a 4-1 lead.
Stone scored twice in the third. His second goal came 36 seconds into the period to make it 5-1, and his third at 13:57 made it 6-3.
Couture scored at 4:57 of the third to make it 5-2, and Meier got the Sharks to within 5-3 at 5:51.
"Not good enough," San Jose captain Joe Pavelski said. "There's always a lot of emotion in playoff games. It's the starts of periods we need to be better at it."
Stone's six goals lead the NHL, and his eight points are tied for first with Stastny.
"That's one of the dominant games I've ever seen from a player in the playoffs," Pacioretty said of Stone.