It depends. It used to be that dead celebrities did not have an expectation of privacy. Today, however, estates are claiming rights that did not once exist and cases are working their way through the court system.
California law has established a specific celebrity likeness use right, but I believe that the celebrity must both live (or have lived) in California and register for the purpose. Neither of these conditions applies to Einstein.
Whether you could get away with applying a specific advertising claim to him, however, might be dicey under a number of statutes.
Although I understand you’re asking a hypothetical, this really is one of those problems that call for an expert lawyer’s opinion.