If a typical passenger plane had total failure of all engines mid-flight, is it possible for passengers to survive?
Air Transat Flight 236 experienced a complete power loss over the Atlantic Ocean in 2001. Yes, all passengers and crew survived after the aircraft glided 75 miles to a runway on the Azores islands.

Even in the event of the loss of all engines, an aircraft can keep its critical electrical systems running thanks to the ram air turbine which allows the crew to maintain control of the aircraft and to communicate with ground crews to determine the best course of action for the situation. This was the case with Air Transat Flight 236.

Moreover, consider US Airways Flight 1549 which experienced a complete power loss after takeoff due to a double bird strike. Even in the situation where the pilot had very few options due to being at such a low altitude and being over a populated area, all passengers and crew survived after ditching in the Hudson River. However, in all fairness, ditching attempts do not normally end well.

In all, complete power loss in a modern airliner is extraordinarily rare. While gathering links for this answer, I ran across the "List of airline flights that required gliding" article on Wikipedia. The short length of the list speaks for itself (4 flights in the last decade).