[bowaggoner]

Both terms are fluid. Most theoretical computer science research is essentially mathematics, at a high enough level. Some wouldn't necessarily call themselves mathematicians unless their graduate training was in a math department; some might. Some would call themselves scientists insofar as they consider mathematicians a subset of scientists. Most would not consider themselves scientists in the sense of natural sciences like biology.

But, most probably don't have a strong opinion on whether/which labels apply! They would say they just do research in TCS.