MS doesn't put a limit on forms but rather total objects.
From Microsoft: A single project can contain up to 32,000 "identifiers" (any nonreserved keyword), which include, but are not limited to, forms, controls, modules, variables, constants, procedures, functions, and objects. Note that the actual number of identifiers is limited to available memory.
Variable names in Visual Basic can be no longer than 255 characters, and the names of forms, controls, modules, and classes cannot be longer than 40 characters. Visual Basic imposes no limit on the actual number of distinct objects in a project.