Gauthier is a larger version of McClemment and I doubt most teams would waste a 1st on McClemment. He'll be a tweener 3rd, 4th liner but since he's not really physical he'll probably never really be a great possession player.
He's the type of player that I would consider revenue neutral when he's at his peak, he won't help TO win because he can't score enough to put TO in a winning situation but he'll probably be used as a PKer and a lineup filler. Our best hope for him is 12 to 15 goals as a 3rd liner with the ability to disrupt the offense of any line he faces.
There's an awful lot more to being a possession player, or being physical, than hitting. Gauthier can be an absolute dominant possession player with his frame protecting the puck. His cycle game is quite strong. I think you'll be surprised. Having said that, 12-15 goals isn't too shabby, especially if he racks up ~25 assists. I wouldn't be disappointed in that at all, thought I do think he's capable of more, and could have seasons closer to 50 points, perhaps higher if he gets top-6 opportunities some seasons. A huge, 40 point defensive master is hardly a 3rd/4th-line tweener.