Adam De Champlain had two goals for the Winterhawks (13-3-1), while Taylor Leier, Taylor Peters and Brendan Leipsic each had a goal and an assist.
Paul Bittner and Tyler Wotherspoon added a goal apiece for Portland while Ty Rattie chipped in with three assists.
Trevor Cheek had two goals and an assist for the Giants (5-12-0) and Carter Popoff, Marek Tvrdon and Anthony Ast each scored once.
Brendan Burke made 14 saves for the win as Payton Lee allowed five goals on 19 shots before getting pulled in the second period.
Tyler Fuhr allowed four goals on 25 shots in 33 minutes of relief.
Portland went 2-for-3 on the power play while Vancouver went 1-for-3.