2010 Cadillac CTS

What kind of quantity are you talking, a full tank. I don't know as though you will cause any damage, but it will probably not run. If you have not cranked it since the event, the contamination is minimal. Unfortunately the fuel tank would have to be removed to drain it. You might be able to run it empty, if you could power the fuel pump. Unlike earlier vehicles, this one has a fuel pump flow control module, and that module supplies both power and ground to the pump.