I've heard it pronounced "Myootchler", "Mootchler", "Mutcher", "Mulcher" (suddenly I'm a gardening tool?) and "Mulchler". It's pronounced just like it's spelled: "Mutchler". Say "butler", and then replace "but" with "much" as in "very much". That's all!
My family and I spent a period of 9 months back in 1981 in Switzerland. Ironically, although "Mutchler" is originally a German name, the German-speaking Swiss people had trouble pronouncing it, because of the Anglicized spelling (it was originally "Mutschler"). They'd try to say stuff like "Moot-kh-lehr".
The spelling gets mangled, too, mainly on mail addresses. I've seen stuff like MUTHCLER, MUTCHELER and METZHLER. One time the phone rang, and I answered it, and the person at the other end asked for what sounded like "Elmachella?" I eventually recognized this as a mispronunciation of a misspelling of a mispronunciation: Someone somewhere had inserted an extra syllable, "Mutch-a-ler", which got written down as MUTCHELER, which got paired up with my mom's first initial, L (L. MUTCHELER), which this lady tried to pronounce as "El Ma-chell-er".
I tell ya, some days it hardly seems worth having a name!