If they supply anything to huawei, they will get barred from buying american equipment. I dont think that they can really hide this kind of things.
We don't know what goes on behind the scenes at Huawei or SMIC. We don't even know exactly how big of a chip stockpile Huawei even has or how long it will last.
For all we know, every night a bunch of little elves sneak into the warehouse and top off Huawei's stockpile with chips fresh from the "reject bin" at SMIC. To the best of my knowledge there is no way to tell which fab manufactured a given chip, especially because they were made with the same ASML machines.
If the US can smuggle strategic amounts of titanium out of Russia without being caught, I don't see why China can't accomplish something similar inside its own territory.