Smith converted off a turnover for his second goal of the postseason. It was only the fourth shot on goal of the period for Vegas.
The Golden Knights, the expansion team that has exceeded expectations throughout the season, have won three games in a row since the Jets claimed the series opener.
"That's what we've done all year," Vegas coach Gerard Gallant said postgame. "We take it one game at a time."
Game 5 will be Sunday afternoon in Winnipeg.
William Karlsson and Tomas Nosek also scored for Vegas.
Patrik Laine and Tyler Myers scored Winnipeg's goals.
Knights goalie Marc-Andre Fleury made 35 saves.
Jets goalie Connor Hellebuyck stopped 26 shots.
Two nights earlier when the Jets lost, they found themselves trailing in a series for the first time this postseason, and now they're in an even more dire situation.
Myers tied the game 5:34 into the third period by sending the puck through past Fleury, who didn't have the net covered as well as it initially appeared.
The Jets were insisting they needed to apply more pressure in this game, and there were signs of that. They registered 12 shots on goal in the first 10 minutes of the third period.
"When you get behind against good teams, it's difficult," Winnipeg right winger Blake Wheeler said after the loss. "You don't like losing and when you have guys who don't like losing, you tend to play pretty intense."
Karlsson opened the scoring with a power-play goal just 2:25 into the game.
Karlsson skated in from the right unchecked, collecting a pass from Jonathan Marchessault and sending the shot past Hellebuyck.
Laine's power-play goal pulled the Jets even approaching the midway mark of the second period.
It was tied for only 43 seconds, as Nosek tallied his first goal of the postseason to regain the lead for the Golden Knights.
For Nosek, it was a rather quick redemption after he was in the penalty box for a tripping violation when Laine produced his goal.
The Jets certainly seemed more active in the second period, posting 15 shots.
--Field Level Media
Winnipeg | Vegas | |
Patrik Laine 1 | Points | Reilly Smith 2 |
Patrik Laine 1 | Goals | Reilly Smith 1 |
Dustin Byfuglien 1 | Assists | Reilly Smith 1 |
Patrik Laine 1 | Power Play Goals | William Karlsson 1 |
N/A | Short Handed Goals | N/A |
Connor Hellebuyck .897 | Save Percentage | Marc-Andre Fleury .946 |
Connor Hellebuyck 26 | Saves | Marc-Andre Fleury 35 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Winnipeg | 37 | 2 | 1-4 | 1-2 | 4 | 31 |
Vegas | 29 | 3 | 1-2 | 3-4 | 8 | 33 |