Scientific theories are factual in the sense they can be backed by evidence. And are made available to be tested. The reason theories exist is so they can be added to if other research shows slightly different results. After several tests though of consistency it's essentially a fact. For example while there is the law of gravity. Gravity is still a theory. Do you believe gravity doesn't exist because it's a theory? Theory doesn't mean hypothesis.
Newton's theory of gravity was for a long time assumed to be "fact." Newton was said to basically have discovered and proven God's underlying formulas for the universe. But all "facts" are interpreted in the light of theory. Even anomalies, or problems with a theory or research paradigm, either must be explained in terms of that paradigm (which is usually what is assumed will eventually happen) or be provided explanation with a superseding or entirely independent paradigm or theory. The Newtonian paradigm couldn't account for the fact, among other things, of the perihelion of Mercury. This was known for a long time, but it was thought that Newton's research tradition would eventually account for it. Well, it didn't, but Einstein's theory did. Newton's theory, while powerful, leaves much unexplained. The existence of the phenomenon of what we call "gravity" doesn't mean that our explanation of that phenomenon, how it operates and how it influences and interacts with other phenomena, is entirely correct. Even general relativity has its problems. Maybe those problems can be explained within an Einsteinian framework, maybe they can't. Whatever the case, to say that any scientific theory is ever anything more than tentative is to ignore the history of science, as well as commit yourself to the logical impossibility of justifying a general empiric principle with a finite number of instantiations.