Caro Kann 2.Nc3 3.Qf3 How to play

How do you play the caro kann lines here?

I'm pretty sure 5...e5 is not the best move, as it gets checkmated in 1.

5..e5 definately isnt the best move due to 6.Qxf7#

I typically play 3...dxe4, which I believe is a main line (it's early enough that it should have been analyzed, but maybe 2.Nc3 isn't common enough that it's treated in books and whatnot. This is motivated by my desire to free up the light-squared bishop (otherwise I'd just play the French!), so play might be like 4.Nxe4 Nf6 and 5...Bg4, 6...e6 unless 5.Nxf6 exf6 which I think is fine for Black (6...Be7 and 7...0-0 should be good).

3...d4 seems premature and just creates an easy target which is hard to defend without overextending (...c5 or ...e5, creating targets which require ...b6 or ...f6 to defend, creating a weak pawn structure far too early in the game), but 3...e6 is probably fine if you don't mind having the LSB locked in for a while like a French Defense. I'd bet this is less likely to happen in reality since White's setup strongly implies he's trying to take and win on d5, which actually suggests he's afraid of central tension. With 3...e6 you pretty much secure d5 for quite a while and if White chops anyways (which is likely if central tension makes him that uncomfortable) you gain a central majority with ...cxd5 (defended by the e6 pawn).

More generally, about 98.6% of the Caro-Kann is pawn structure, in fact piece placement is almost arbitrary (except that, of course, it must follow the pawn structure and so it is not so arbitrary!). When facing an unfamiliar line, follow good opening principles but especially pay attention to the pawn structure that each move leads to (e.g. 3...d4 leads to a disasterous structure, while 3...e6 or 3...dxe4 lead to much more stable structures although the latter of these might be rather drawish).

Is it still mostly about pawn structure even with unorthodox moves like Qf3?

My bad 5... e5 gets mated in 1

what about 5...c5 or 5...Nf6  ? Or whats the best move in your opinion

Short answer, yes. The primary advantage of playing the Caro for Black is the superior pawn structure (it sure as heck isn't an easy development!), and Black's plans tend to revolve around obtaining some sort of static advantage and forcing his way into an endgame with that advantage. Unless White launches a dramatic tactical flourish (in which case the "Defense" part of the name comes into play), an unusual move might take Black out of his book lines but should not change his overarching goal out of the opening (unless of course there is an obvious advantage to be gained, i.e. White blunders).

Wow lol ty..

Can you teach me what other openings revolve around like Caro-Kann revolves around the pawn structure?

And how would you claim your easy win in this line if black plays greedy which is a bad idea

1.e4 c6 2.Nc3 d5 3.Qf3 d4 4.Bc4 dxc3 5.Qxf7+ Kd7 6.dxc3 Kc7 (i think other moves besides kc7 gets mated asap)

Pawn structure tells you a lot about the plans for both sides in nearly all openings.  What's more is there are not that many different basic structures to learn.