I have never been able to find a reliable link, study, or article, though I've usually heard it placed at 80% and as special needs kids, not kids with autism.
My experience, that I readily is admit is anecdotal, is the opposite. My son is 7 and we've reached the point where a lot of our friends and acquaintances with same age kids are divorcing. They mostly have typical kids, one has a kid with mild ADHD. The friends with special needs kids (ADHD, ASD, SPD, cystic fibrosis, bipolar) are not divorcing. I do have one friend who is a single mom with a son with ASD, but they split when he was 6 weeks old.
I'm not sure why, though an informal survey, revealed a lot mothers snorting and saying "Who can afford to?" I'm not sure if my life and the people in are typical or not, but I think people divorce because there are underlying issues in the relationship Maybe, a child's disability brings those issues into focus, but doesn't cause them.
My husband and I have some major difference in how we parent our child. Those would be an issue with any kid, but with a kid with a disability, DH's go with the flow attitude and lack of consistency were a bigger deal to me, especially when our son was small. My control freak, research everything nature is better suited for our son at this time. I guess what I'm saying is our son's issues made this a bigger issue, but didn't cause it. I think that could be true of any stresses in a marriage; finances, in-laws, careers, death of a child.