It is very unlikely that they are actually backed 1:1. They fired their independent auditor over some kind of disagreement last I heard. This does not sound good, but the problem is that USDT is so integrated in the crypto markets now, its really going to hurt bad if it collapses. Honestly, I would like to see more exchanges SLOWLY start trimming away USDT pairings to solve this so there is no sudden panic. IF it can happen slowly and carefully I think we can escape this with minimal damage honestly.