Currently my uncle is 38 years old. not covid related. he was perfectly healthy but now he is in critical care with total organ failure, in a coma, and on a ventilator. honestly does he have any chance to survive?

In absence of data involving the underlying diagnosis, and understanding of the evolution of this critical process, it is not feasible to be accurate or precise. The prognosis sounds very poor, especially if there is involvement of liver, lungs, and/or heart. An EEG might assess brain stability, but a conference with his doctors is more direct regarding appropriate management. Wish you the best

He is on life support, prepare for all possible outcomes while hoping for the best. His current ICU team would be best to discuss prognosis at this point.