Holloway, the No. 14 pick in the 2020 NHL Draft, has six points (four goals, two assists) in four games this preseason.
Zach Hyman had a goal and two assists, Warren Foegele scored twice, and Jack Campbell made 28 saves for Edmonton.
Conor Garland had a goal and an assist, Christian Wolanin had two assists, and Collin Delia made 29 saves for Vancouver.
Holloway gave the Oilers a 1-0 lead at 10:39 of the first period.
Nils Hoglander tied it 1-1 at 4:24 of the second period with a power-play goal, but Hyman scored his own goal on the man-advantage to put the Oilers back in front 2-1 at 11:50.
Holloway scored his second of the game 26 seconds later to push it to 3-1.
Garland then cut it to 3-2 at 13:08.
Tyson Barrie responded at 18:48 to give Edmonton a 4-2 lead, and Holloway completed the hat trick at 17:19 of the third period to extend the lead to 5-2.
Foegele scored his first goal of the preseason at 18:05 to make it 6-2. He scored again 51 seconds later for the 7-2 final.
