Do you want to know why it's J-if and not Gif?
G sounds, come from the back of the mouth
J sounds, from the front
giff, sounds like a three chinned downey spitting all over the place with no vocal control
to make G sounding words that don't sound retarded, you need to add a strong converse sound, like Guardian, with it's hard R (unless you're nonrhotic speaking, which sound exactly like the above retards) , or Gut which deflects with a T.
since English breaks pronunciation conventions constantly, and is well past the point of bastardization, and there's probably as much bastardization that's been standardized as there are what's left of the original conventions, the pronunciation of a single word is irrelevant.
The funny thing about GIF, is our generation was raised with the word without having adults who ever used it, it was kids on their parents computer mostly that went about establishing it into the lexicon, hence the division of the pronunciation, and thus the question how many times before has something similar happened.
TLDR; people that use the G sound for GIF specialize in deep throating dicks