Kuemper, making his 21st consecutive start, allowed two goals on 18 shots.
Coyotes coach Rick Tocchet said Lewis' stick got through an opening in Kuemper's mask, and the goalie's vision was blurry afterward.
"But he feels OK, and he seemed to be in pretty good spirits. … It looked bad, but I think he's going to be OK," Tocchet said.
Drew Doughty scored into an empty net with 45 seconds remaining for the 3-1 final.
"They might have got 50 shots but I thought our guys played super hard in front, tied up sticks and cleared rebounds and did a good job on their top guys," Campbell said.