Sam Steel collected the secondary assist and now has points in three straight games (1-3=4).
Anaheim has scored the game's first goal 29 times this season, second-most in the NHL (Washington, 30).
The Senators answered less than two minutes later on a terrific play by forward Tyler Ennis, who batted down a breakout pass at center ice, spun away from a Ducks defender and ripped a shot over Gibson's glove.
Defenseman Josh Manson, making his second appearance since returning from the NHL's COVID-19 protocol, left the game in the first period following a hit by Senators forward Brady Tkachuk and did not return with an upper-body injury.
Ottawa controlled much of the second period, peppering Gibson throughout the 20-minute stanza and applying pressure deep in the Ducks defensive zone, but Anaheim's All-Star netminder kept his team in the game much as he has all season long.
The Senators outshot the Ducks 18-4 in the scoreless middle frame.
Ottawa's relentless offensive attack continued in the third, especially so on a power-play opportunity when Hampus Lindholm was whistled for hooking, but the Senators had no answer for Gibson even with the man advantage.
Moments after one Ducks All-Star kept the game tied, the other broke the deadlock on the opposite end of the ice. Terry took a pass from Getzlaf at center ice, dragging the puck towards his body and firing a wrist shot by Forsberg, clinching his first career 25-goal season.