Jacob Markstrom allowed five goals on 34 shots in 51:34, and Thatcher Demko made five saves in relief for the Canucks, the No. 5 seed.
"They're a fast team, they're a good team," Vancouver coach Travis Green said. "We just need to play better; we didn't play very well tonight. We're definitely not going to just flush it and move on. We'll watch the game again, we'll meet with our team like we have whether we've played well or didn't, analyze our game. We have to be better with the puck, that'd be a start, and we have to play better."
Jonathan Marchessault scored on a wrist shot from the bottom of the left face-off circle to give the Golden Knights a 1-0 lead at 11:37 of the first period.
Vegas scored three goals in the second to take a 4-0 lead.
"That's our game (in the second period) and something we've been building on prior to the NHL pause (on March 12 due to concerns surrounding the coronavirus)," Golden Knights coach Peter DeBoer said. "We want to come out in those second periods and take advantage of the long changes and beat teams with our depth. We're tough to play against when we're playing like that."
Smith scored on a rebound on the power play to make it 2-0 at 2:13 before Stone deflected a Nate Schmidt shot for a 3-0 lead at 11:35.
Tuch caught up to a pass by Nick Cousins from the Vegas zone inside the Vancouver end and scored on the rush to make it 4-0 at 16:34.
"We were good on the forecheck, and our defense also did a great job being able to jump in there, and when we're able to use them as a five-man unit, it makes a huge difference because we're able to spread out their team defense," Smith said. "That puts a lot of pressure on them, and we caught them a couple times tired out there. We were able to roll over shifts; it's amazing how much offense you can create when that happens."