I agree with David; gris-gris doesn't influence Cajun or zydeco in any quantifiable way. That could be a very interesting angle for a new C&Z band to emerge with! A lot of minor key tunes with dark subjects and chants, maybe some gothic make-up and snake skins... a little candle burning from the stage. Hey! Don't let me give you any ideas! But I bet the idea would sell!
Zydeco Gothica... WHAT A KICK! You'd always have gigs at Mardi Gras and Halloween!
The only C&Z artist that I'm aware of that even approched this angle was Sunpie... when, for a short stint, he dawned the hat and eyeglass in the stylings of Baron Samedi.
That isn't to say that certain superstitions aren't practiced by C&Z musicians. I'm sure if they were, they'd keep it under their hat. Most visions of voodoo evolve in -- or around -- New Orleans. It's become a source of tourism and income!
Voodoo and Louisiana have been associates since the arrival of slavery; where slaves of West African and Santo Domingo origin brought their beliefs and rituals to the plantations across the South. Many of the descendants of these slaves ended up in southern Louisiana, particularly in New Orleans.
To this day, a lot of Creole customs such as painting their front door blue, scrubbing the front porch with brick dust and covering mirrors during thunderstorms, just to name a few, are practiced. Many of the people that act on these traditions do them because their grandmother or great-grandmother did these things and are unaware of the fact that they originate in superstition. It's one of many vital and interesting elements in the psyche of "Louisianaism."
Check out some of Dr. John's [ATCO label] recordings from the late 60's and early 70's for some Louisiana music that is influenced by "hoodoo"... and more recently, music by a New Orleans' artist, Coco Robichaux.