This is the first time I’ve heard Yoga referred to as being “occult”.
By those who believe what they believe and that those who don’t are sinners....
Anything that might potentially erode Big Religion's profit margins routinely gets labeled "occult". ;)
Yoga does usually have a spiritual component. It may be harmless surface stuff (in fact, I think it usually is in the U.S. because most yoga instructors don't have the background to get heavily into the psychic end. Even those who try are usually pretty ignorant.)
But yoga theory does involve religious practices which are incompatible with Christianity. So you could have a very heavily religious yoga class (probably one taught at a Hindu temple - there's one around the corner from us.) I would not take a yoga class there, because that would be clearly incompatible with my beliefs.
However, your average YMCA yoga class probably is taught by somebody who has only a superficial acquaintance with the spiritual aspects of yoga. And worrying about occult influence in that sort of class is right out there with worrying about Harry Potter. There are far more important occult influences to worry about.