I mean, I would make the argument that Canadian media isn't being bought by leftist ownership groups from the US in the same way as, for example, Postmedia has almost monopolized Canadian newspapers through American right wing ownership. Major media seems like a more direct and present form of political influence than a more natural spread through observation like what I believe you're describing.

...would you say that leftist people in Canada are strongly getting influenced by people like Bernie Sanders and AOC and that it should be considered foreign interference?

No, because Sanders and Cortez would be centrists to mildly leftist in Canada. Half the Liberal party, most of the Bloc and all of the NDP are well to the left of Sanders.

Only in the US, where the Overton window is from "mildly corporatist neoliberalism" to "full-throated fascism" do people like Sanders seem at all radical.