A famous bearer is Canadian actor Gil Bellows (born June 28, 1967). He is well-known for his work in American television, specifically as Billy Thomas in "Ally McBeal" and Matt Callan in "The Agency".
This might be a rather obscure bearer, but in an old Namco game called The Tower of Druaga, the hero was named Gil. In his case it was short for Gilgamesh. That's probably the main association I have with this name.