The 18-year-old forward has scored two goals and 10 points in four games this week and now has 26 goals and 61 points in 51 contests, which leads his club in both categories.
Michael St. Croix scored twice for the Oil Kings (35-11-5), who extened their win streak to five games, and Dylan Wruck had a goal and two assists.
Brandon Baddock, Trevor Cheek and Dysin Mayo also scored for Edmonton.
Mayo's goal was his first of his WHL career.
Josh Derko scored the lone goal for the Silvertips (21-27-3), who lost in regulation for the first time in four outings.
Laurent Brossoit stopped 21 shots for the win as Christopher Tai took the loss after allowing six goals on 30 shots through two periods of action. Ty Rimmer stopped 13-of-14 shots in relief.
Edmonton's league-best power play went 4 for 9 while Lethbridge failed to score on four chances with the man advantage.
Cheek opened up the scoring on the power play for Edmonton at 9:40 of the first period, however Derko responded for Lethbridge only 25 seconds later.
Mayo put the Oil Kings up 2-1 before the opening 20 minutes were through and then Edmonton exploded for four goals in the second period, including three more on the power play, to blow the game wide open.
Wruck scored first with the man advantage and St. Croix added two more for three goals in the span of 4:37.
Samuelsson scored in the final minute of the period to make it 6-1 after 40 minutes of play.
Baddock tacked on Edmonton's seventh goal at 15:27 of the third period.