Killorn's second power-play goal, the fourth goal of the second period, made it 5-1 off a centering feed from Kucherov at 13:12 after Kyle Palmieri was called for unsportsmanlike conduct.
"Getting those goals there on the [power play] is big," Johnson said. "The [power play] is out there to at least get you the momentum, but any time you can get a goal or two like we did, that's huge."
Vatanen made it 5-2 at 19:34 of the second period, and Blake Coleman scored on a one-timer to make it 5-3 at 11:57 of the third period. The Devils could have gotten within one goal, but a video review at 16:46 determined a shot by Miles Wood did not completely cross the goal line.
"We came out in the third and played the right way," Devils captain Andy Greene said. "We have to do that in the first and go from there. We can't have these three-, four-, five-minute lapses in periods against a good team that took advantage of it, and we just can't have those kind of mistakes in this series."
Point gave the Lightning a 1-0 lead, scoring his first Stanley Cup Playoff goal at 12:15 of the first period.
"I was just so excited to put one in," he said. "It's kind of a feeling I can't explain. It was a great play by Johnson to get it to [Ondrej] Palat and he found me in open ice on the wing."
Hischier tied it 1-1 with his first NHL playoff goal at 13:38 of the first.
Lightning forward Ryan Callahan sustained an upper-body injury in the second period and did not return. Defenseman Dan Girardi didn't play in the third period.
"That was a little bit of an issue for us, too, we dropped down to five defensemen and 11 forwards," Tampa Bay coach Jon Cooper said. "It kind of changed things, a little bit, obviously for us. But no update yet."