Hard G is correct. No question about it. Unless someone can show that .gif originated from a French (or other foreign) word.
Giant, giraffe, gin, etc - all french (or european) basis.
Its not like these words came suddenly into the english language and we had guys sitting around a room going, "Ok, Giant - lets pronounce the g as a j. Next word..."
Word. Origins. Matter.
The problem with Wilhite is he's a dumbass and pronounced it wrong from the start.