Considering the quantity of steel used in a single knife and, the actual intrinsic value of that weight of steel, knife prices should be relatively unaffected.
In a custom knife, what are paying for? Labor and artistry or, a small piece of steel?
In a production knife, you are dealing with steels that are comparatively cheap relative to things seen in higher end customs. Good old generic carbon steel may be hit with the tarriff but, it is also relatively cheap compared to newer super steels. What you may see to a lesser effect, is a trend to move from an inferior imported steel to a more expensive but, better steel made in America. No, you're not going to see a switch from 1084 to S30V but, a company using imported ATS-34 maybe able to upgrade to BG-42 at no imcreased cost or a neglible cost increase.
Knifemakers or knife companies that raise prices to match the tariff, may get accused of price gouging if nothing else changes.
All that being said, the steels I prefer, especially in custom knives, are made here in the USA. The few commercial holdouts using ATS-34 may finally switch to CM154 but, most have already done that.