actually, the 'machine' is trained with a voice model. so, when you're saying that you'll let a machine decide, in this particular case you're really letting google decide (and expecting them to have baked in an appropriate pronunciation of gif).
the google translate tts models are older than their android models (particularly network tts), and it seem as though it still treats it similarly -> http://bit.ly/12tpCol
http://translate.google.com/#en/en/GIF%20or%20JIF...%0Agif%2....
Google's Text-to-Speech seems to pronounce it with a Soft G.