Blank forms are not in general terms protected by copyright law. Even if the form has a lot of design flourishes, it's still considered a tool to collect data.
Some elements of the form may hold copyright in and of themselves, for example:
but the form itself is not a "creative work". The same is true of things like blank diaries, bank checks or sheets of headed notepaper.
The answer depends a lot on the country you live in and, if different, the county your users reside in. In the end, you will probably need a lawyer to get a reliable answer.