Both signed or just one? IF genuine (1st hurdle), a very quick peek suggest perhaps 1k-2.5k or a bit more possibly (I don't know sports - was this a very special game etc.) but you'll need good certification to realize the full value, whatever that might be, and then a sale venue. One pair (both signed) that I saw had papers from JSA. There is PSA/DNA, of course. Sports guys here will have suggestions for who is good for this sort of item - perhaps an individual authenticator. I am just trying to give you some kind of answer, I am not commenting on the authenticity of the signature nor do I claim my rough estimate at value is anywhere near correct. RR had a single signed shoe for $779 or so in 2014. Condition is paramount - after authenticity. Hope this helps.
If real, I'm no Shaq expert, they have value. But without some serious provenance there is no way to validate that the shoes were game-worn much less specify which game they were used in. Did he provide any documentation to the claim they were used in a Finals game?