Yes, with proper preparation
Real Venetian plaster can be applied over drywall as long as the wall is prepared correctly. That means the drywall is skim-coated smooth, any imperfections are removed, and the surface is primed with the right primer so the plaster bonds evenly. Venetian plaster is unforgiving; every flaw in the wall shows through the polish, so the prep is where a good job is won or lost.
Why prep is the whole story
Because the finish is polished and reflective, it magnifies anything underneath: a bad drywall seam, a roller mark, a dip in the wall. A skilled installer flattens and primes the wall first so the finish reads as a single, deep, marble-like surface rather than a shiny coat over a rough wall.
What to ask before you start
Ask whether the installer will skim-coat and prime the drywall first, whether they apply the plaster themselves or subcontract it, and whether it is real lime plaster or a paint-based imitation. If the answer to any of those is vague, keep looking. Genuine Venetian plaster over well-prepped drywall lasts for decades.