Kevin Porter had the only goal for the Sabres (16-18-6) and spoiled what could have been Ondrej Pavelec's first shutout of the season in the third. His shot glanced off Wheeler. Pavelec finished with 29 saves.
It was the second win in a row for the Jets (20-19-2) during a six-game homestand they pretty well need to sweep to have a decent chance of making the playoffs.
It was rinse and repeat as Gagnon fired a slap shot from the same spot on a pass from Dustin Byfuglien.
Just before the period ended, Bryan Little and Ladd got a jump on a race to the Sabres' net and Ladd fired one past a prone Miller.
Wheeler finished things off with an empty-netter just before the end of the third.
The Jets dominated early. The first period looked like a Winnipeg power play until the last few minutes.
It took almost seven minutes for the Sabres to put a shot on the board.
Both teams struck out on their real power-play opportunities — two for the Sabres and one for the Jets.
But both defenceman Tobias Enstrom and Little headed to the Winnipeg dressing room during the first. Little took a puck fired by a teammate but it wasn't clear what happened to Enstrom.
Little returned but Enstrom did not.
Notes: Pavelec passed 6,000 saves Tuesday night. Winnipeg has won every game this season that Kane has had more than one point.