He's a center. Any one who says differently hasn't watched him longer than a 2 minute highlight reel.
"But can he play it in the NHL?!!?!"
I can't think of a more tired retort. The reason that is raise so many times for junior players who are "C"s is because puck dominant scorers often play C because it gets the puck on their sticks more and lets them score more which flat out doesn't work in the NHL unless you're otherworldly. Kasper is literally the antithesis of this. He oozes all the high quality traits you want from a C - 200 ft, selfless, physical, can play in the corners and down low, doesn't hang on just the perimeter, can shoot, looks to pass and set up his teammates, doesn't shy from the body, thrives defensively and is tenacious.
THAT's why we have that stupid "CAN HE PLAYZ CENTER IN THE NHL?" - too many score-only forwards in juniors where they can get away with just doing that and find that the responsibilities of the C are much more serious at the professional level. Kasper does all of it.