The best-of-seven series now shifts back to Kamloops, B.C., for Game 5.
Kale Kessy had a hat trick for the Blazers, while Marek Hrbas's goal late in the third period forced overtime.
Ben Walker, Logan Nelson, Brandon Fushimi and Jamie Crooks scored for Victoria.
Cole Cheveldave, made 20 saves for the victory, while Royals' goalie Patrik Polivka made 43 saves in the losing effort.
The Royals opened the scoring with a pair of first-period goals. The first from Crooks for his second of the playoffs, and Nelson made it 2-0 on the power play.
Kamloops got one back at 19:42 of the first as Kessy scored his first of the night to make it 2-1 heading to the second.
Kessy tied the game for the Blazers at 1:22 of the second to pull Kamloops even, but just 28 seconds later the Royals answered back as Fushimi scored to restore Victoria's lead.
Kessy completed the hat trick, making it 3-3, 7:16 into the second.
Walker scored on a 5-on-3 power play to give Victoria their third lead of the game.
Kamloops drew even once again in the third as Hrbas scored his first of the post-season.