yes, the creator of the word gif said "jif" but the first letter of the word stands for graphical (a hard G) so i pronounce it with a hard G. also, how many words begin with a G are pronounced with a J do you know?
This brings up the whole ordeal of more than just GIFs, where as people are now locked into an eternal war for pronunciations of things. Like UPlay being pronounced with an Unlauted U. Who cares how its pronounced? Ubisoft is French Canadian, there's no pronouncing it right ever!
It's JIF, doesn't matter what the letters mean in it (just because Graphic is said with G, doesn't mean you say Gif). It's basic English pronunciations, you don't say GIRAFFE, you say JIRAFFE, and any other word where there's a G and after that there's an I, it makes it J. :^)
GIF, hard G. This is one of those cases where the creator is wrong about his own creation. Y'know, like Ray Bradbury insisting that Fahrenheit 451 was about the dangers of television rather than of state censorship and anti-intellectualism.
... Though I will admit that Giraffic Interchange Format is a funny idea.