To make a hide, you need to steam, smoke, and degrease it. I doubt any of this could be done in survival situations. Despite the website's dedication to wilderness survival, the link here suggests wilderness preparation, but not necessarily in survival situations:
If you used the hide from a killed animal, you have the issue of dealing with blood and other liquids, would be a disease risk to you. So you'd have to process it first, and, given the survival aspect of your question, I'm not sure this is feasible. If you can make a fire for steaming, it stands to reason you can use that fire for warmth.
Here are more "survival" methods:
Survival Skills: Brain Tanning Hides
9 MONTHS OF WILDERNESS SURVIVAL
In the end, I think your efforts are better focused on shelter, warmth, finding food and water, and getting found. I don't think a dead animal is going to help you, however useful it may seem, other than as food.