Quote Originally Posted by Jaitne
So it's their thought on it, it also doesn't go directly into the pronunciation of the word.
If you follow the links for "geis" and "geas", a pronunciation is given in IPA. It's identical to the one that is given in the link you posted. I was mistaken earlier when I looked at that page, thinking there was a dipthong after the "e" vowel, but it seems like it's "Gesh" after all.

Case closed.