 According to the United States Census Bureau, the township has a total area of , of which, of it is land and 0.02% is water.Gaines Township is bordered by Clymer Township to the north, Shippen Township to the east, Elk Township to the south and Potter County to the west.As of the census of 2000, there were 553 people, 259 households, and 155 families residing in the township.