Yes having the ankle strap higher can help toeside carving, but boot stiffness and binding stiffness (and of course the board) also play big factors. Heelside carving response comes from the highback, so you won't lose anything by moving the ankle strap higher.
Another thing that helps toesides is increasing the highback angle. Why, you say? Because it forces you to bend your knees more, and thats where the real power comes from. For a real strong toeside carve, you should be driving your knees into the snow.