According to The Huffington Post, a man by the name of Maurice Tillet shares many visual characteristics associated with the fictional character thanks to a disease called acromegaly, which is a hormone disorder. Not surprisingly, DreamWorks has offered no official position on whether or not the man from the 1930s and 1940s inspired their lovable ogre of character, and the lack of comment from the studio is only adding fuel to the fire. Still one glimpse at the photographs and fans can probably make up their own minds on the issue.
While DreamWorks is likely avoiding confirmation of the issue due to royalty concerns and payouts, the theory is difficult to actually prove regardless of the similarities between the real life man and the fictional character. Fans have a way of seeing what they want, and of course corporations responsible for fictional characters have their own opinion. Still, actually proving without a doubt someone inspired anything without confirmation of the creator is an extremely difficult process.