Let's look at this question from the perspective of the 4 Priorities:

1) Shelter: one can usually be put together faster if one has the appropriate cutting tools for saplings, vines, etc.

2) Water: requires a vessel to hold the water if it's going to be purified by a filter, chemicals, or boiling (fire). In the case of boiling, a firestarter of any type is a good thing to have.

3) Food: a knife can be used to cut vines & lines; striker on a flint or ferrocium rod; a spear point, skinning/prepping; cooking.

4) Fire or a source of heat: a knife can strike sparks; can be used to prep tender & wood; can make firemaking tools, a bow drill or a trough. A firestarter of any kind is good to have.

IMO: a good sturdy knife(ves) is actually more important than a firemaking kit(s ) but I carry multiples of each kind of steel tool and of fire making means (call me "insecure")