Bolin wins due to him having lava bending. Toph not going be able counter lava bending. The more earth the earth bender gives to lava bender the more lava the lava bender has. Just remember what Bolin said to Ghazan when they was fighting. Bolin kept earth bending and Bolin said "its like Im giving this guy more ammo wanna trade"? So Tooh using earth agaisnt Bolin not going be smart for Toph to do. Basically Bolin wins due to having lava bending.