Am I screwed
 

Have a 2014 Silverado 2500 duramax guys at work put 9 gallons or a 1/4 tank of gas in it and drove it, has 3/4 tank now, it started but it kinda rumbled and shook can I save it,

You can only try- remove gas-diesel mix from tank, lines, fuel cooler etc, replace fuel filter and try with fresh diesel.
If it still acts up it sounds like high pressure pump+injectors time. Not sure if this repair does not exceed the value of the vehicle.

Good Luck!

The new diesels have catalytic converter and / or def injection.

If this question was posed on our old 12 valve trucks, which have none of that crap, you would simply add a couple gallons of new engine oil to the tank, top off with fresh diesel, and drive it.

I agree with Alpine. Drain the tank, refill with diesel and see what happens.

New emissions parts may or may not require replacement . you might get lucky, and all would be fine.