As far as I can tell the two have different etymologies and have both possible pronunciations, CLUH-J and CLOO-J but seem to be used interchangeably. I had not idea CLOO-J even existed until my school business librarian used it.
- Anybody can ask a question
- Anybody can answer
- The best answers are voted up and rise to the top
In thirty years as an engineer, the only pronunciation I have heard from other engineers is CLOO-J.
On the rare occasions when I heard someone say CLUH-J, the speaker was NOT an engineer and was pronouncing the word as they had seen it written: kludge.
I've also seen and heard both. In my experience, kludge is more common these days; kluge seems to be used by older programmers/engineers, or those who believe that it's more correct because it's apparently older. To me, the kludge spelling and "fudgy" pronunciation seem more American. That is, I can see it looking and sounding more comfortable to average Americans, while the other may seem a bit stilted (trying too hard to maintain foreign origins).
I know you have to be careful when relying on Wikipedia, but I think its article on this subject is pretty good.
I always use the CLOOJ pronunciation, because that is how I've always heard it. In fact, I've never heard it the other way.
Nevertheless, I always spell it kludge, possibly because kluge always brings to mind the German word meaning "clever" and is pronounced "KLOO-GEH".