I think you can apply a version of KISS to this question. KISS can be Keep It Simple Stupid by looking at what "survival" you're talking about. Then it can be Keep It Small Stupid to fit that survival model you're identified.
Most of the time a small blade around 3-3.5" is all that is needed for a knowledgable person to use in "survival" situations. In some cases a larger blade is a big advantage though (machete), but they are not common.
Keep the guards small. A knife with a cross guard or a single guard that is designed for "fighting" knives isn't good for a "survival" knife. You want to be able to keep your fingers off the blade, but you don't need a big piece of metal keeping the blade off of the cutting surface.
Most of the time a small blade around 3-3.5" is all that is needed for a knowledgable person to use in "survival" situations. In some cases a larger blade is a big advantage though (machete), but they are not common.
Keep the guards small. A knife with a cross guard or a single guard that is designed for "fighting" knives isn't good for a "survival" knife. You want to be able to keep your fingers off the blade, but you don't need a big piece of metal keeping the blade off of the cutting surface.