A nerd battle has been won
English speakers often pronounce "GIF" with either an affricate as in "giraffe" /dʒɪf/ or a plosive as in "gift" /gɪf/. The format's creators are quoted as using an affricate to pronounce the acronym. There is plenty of evidence to suggest this, much of which can be found here. However, many people use the plosive pronunciation in daily conversation. The affricate was used as the developers had a sense of humour "Choosy Developers Choose GIF", making a play on a then-famous commercial for peanut butter. Outside of the English language there are a number of further variants.