From what we know, Wlad absolutely clowned him in sparring. But, Wlad has not been looking great lately. I'd want to see the Fury rematch before making a call. If Wlad is in any sort of form he breaks him down and KO's him at rounds 4-6.
so far wlad when prime has shown he might well outpoint wildman after an early scare, who has as his best acheivement outpointed a past prime Le Stiv. A reverse stoppage is possible, given wlads chin paucity and possible problems with large opposition, but its hard to bank on that since Wilder has not proven his stopping ability at world level. You might argue that Wilder is above the Sanders failed contender level that can easily kill wlad in seconds, but I dont think hes proved that yet, even though he has a title and has defended it - all his defences have been substandard weak contenders such that hes defending an "international" level belt, not a world one.
Wlad lost to ****en Fury. Nuff said. Wlad might beat Fury in the rematch, or maybe not...but he's washed up. Wilder would knock him out with the first clean shot he lands.