Here is a list of active chapters at UT:
Acacia
Alpha Epsilon Pi
Alpha Tau Omega
Chi Phi
Delta Chi
Delta Sigma Phi
Delta Tau Delta
Kappa Sigma
Lambda Chi Alpha
Phi Gamma Delta
Phi Delta Theta
Phi Kappa Theta
Phi Kappa Psi
Pi Kappa Alpha
Pi Kappa Phi
Sigma Alpha Epsilon
Sigma Alpha Mu
Sigma Chi
Sigma Phi Epsilon
Sigma Pi
Tau Kappa Epsilon
Theta Chi
Zeta Beta Tau
Zeta Psi
I think the thing with UT's Greek system is that the "top" chapters for both sororities and fraternities is that they have so much history. These chapters have all been here for over 100+ years and have since acquired a lot of $$$ and nice houses. SAE, SigEp, Fiji, KA, Delt, Kappa Sig, ATO, ZBT, and a few others all have big houses with lots of members that pay EXTREME amounts of dues and these houses have pretty much always been on top. It's like paying for college twice, but when you have that much cash flow they throw the biggest and best socials and have the most to offer to top prospects in rush. The smaller fraternities just can't really compete and thus are nearly mute in the university's social scene which thus in turn creates a cycle of not recruiting as well as the other established chapters.
Regardless it's always sad to see a chapter go...especially a historical chapter that's been around since 1886.