Okay, it looks like todays "survival kit" more resembles a kit to make it through the night or some essential gear till you find your way.
Other than all the mandatory items listed here...I'll add one for duration survival. Bring some snare wire, know how to use it before going into the wilderness. Use snares to get food. No energy expended unless going to the snare and back. No endless roaming around hopefully making a shot.
If you are stuck for over a week and eating rabbit/squirrel and NOTHING else....you have to munch down a couple of bones. The meat is too lean, and you can get protein poisoning if you dont get some fat/marrow in your system.
Get a good book on survival and READ it. Try techniques as some said here in your yard.
My buddy and I stayed in a spike camp in northern Alberta in tents in early spring. We were on the opposite side of the Peace river than the few people and our guide living in the area. No situation happened, but we were ready. We made soup out of cattail roots and dandelion leaves, made deadfall traps for fox size game, luckily did it all for fun and experience rather than HAVING too. But learned a lot!
Here is one of the smaller deadfalls on a game trail. Didn't get any game, a bear destroyed it!