Which style has more fans?
Well actually, I'm pretty damn sure indy style wrestling has more fans. Don't go crazy, I'll explain.
Indy wrestling fans watch WWE/TNA because it's there to watch, they go to WWE/TNA events because they're there to go to. Ask them if they like WWE or TNA and they'll say "fuck them, I'd rather be going to ROH shows, but they never come to my town." They are still considered "fans" though because they pay for the product.
Then there are the indy wrestling fans all over the world that refuse to watch, pay for, or even pay attention to WWE or TNA. They're wrestling fans.
WWE/TNA fans watch WWE/TNA because they either have never heard of independent wrestling, they are little kids, they are older people that grew up with WWF, or they just think that WWE and TNA are the only wrestling companies in the world. You'd be hard-pressed to find someone (someone that appreciates the actual wrestling that is) that watches WWE or TNA and comes across ROH and doesn't jump ship to watching indy wrestling.
So to sum it all up.
Indy fans = Large amount of WWE/TNA fans + Exclusive indy fans
Sports Entertainment fans = The rest
There are FAR, FAR, FAR more independent promotions in the world than there are promotions like WWE or TNA, so to even question the amount of fans each style has is crazy.