Can Tether survive a net outflow? Probably not. They don't have the collateral.
Dai is really a derivative of Etherium. Dai is backed by Etherium at 150%. So value in Dai is at risk if the price of Etherium drops more than 1/3. Etherium dropped by half back in May 2021, but recovered. DAI could have crashed at that time if it faced a net outflow. It didn't, though.
The real question is what happens in the next recession.