I think the broader, and more pertinent questions, are - "What is a survival knife?, and "What is a survival situation?"

Part of the answer to the second question is that the survival situation is unanticipated. There is an earthquake, or unforecast storm, or a sudden wildfire, and your circumstances are altered drastically. The result is that you are probably carrying your tiny little EDC.

Frankly, I would be perfectly happy is a tough situation with a SAK or one of my Moras, even though I won't have a full tang. I would be really happy with a Wave, especially if I would also have its accessories (bit kit, extender, etc). With a multitool, if you are faced with a need to trash something by prying or whatever, i can sacrifice an accessory on the tool and leave the blade still sharp and functioning.

The most important element is survival is the will to survive (See Laurence Gonzales' Deep Survival and others).

The steel behind the blade matters more than the steel within the blade.