I used to pronounce it with a hard G because I had only read it and I assume that's how an English speaker automatically would pronounce it unless specifically learned otherwise. Of course, there are words like "giraffe" but these are learned. I think the soft G exceptions are generally learned and for most people "gif" would mainly be read first, and they would default to the hard G.
However, over a decade ago I read that the creators wanted it to be "jiff" so I switched to that, much to the annoyance of nearly everyone I meet. I think using the hard G must be in the majority since anyone who hasn't read that it should be "jiff" would automatically pronounce it as "gif". Most people will have read the word first rather than hear the word first.