The 20-year-old forward, who was a third-round pick (No. 76) in the 2020 NHL Draft, has five points (four goals, one assist) in two games this preseason.
Erik Karlsson had a goal and an assist, Timo Meier had four assists, and Tomas Hertl had two assists for the Sharks, who also lost a split-squad game 4-1 to the Anaheim Ducks on Friday. James Reimer made 27 saves.
Jack Eichel had two goals and an assist, Reilly Smith had a goal and an assist, and Phil Kessel had two assists for the Golden Knights. Adin Hill made 32 saves.
Mark Stone, who had back surgery this offseason, made his preseason debut for Vegas. He had one assist in 15:59 of ice time.
Karlsson gave San Jose a 1-0 lead at 6:26 of the first period, but Eichel tied it 1-1 at 18:30.
Gushchin made it 2-1 at 5:35 of the second period before Matt Benning pushed the lead to 3-1 at 8:59.
Jonah Gadjovich scored 57 seconds later to make it 4-1.
Smith converted on a power play at 13:34 to get Vegas to within 4-2, but Gushchin restored the three-goal lead at 15:41.
Eichel scored his third goal of the preseason 51 seconds into the third to cut it to 5-3.
Gushchin completed the hat trick to extend it to 6-3 at 4:37, and Luke Kunin scored at 11:48 for the 7-3 final.
