I'd say that "the truth" is what is, whether anyone sees it or understands it; or whether anyone can, say, prove it in court (to meet standards of proving something) or not; or whether someone/something (like Science) can say with complete (but "legitimate", rather than just a matter of of over-blown/inappropriate confidence) certainty that there is nothing more about any particular "truth" that could be learned and could reveal what has been thought of as "the truth" to have been incorrect/incomplete).
There are different types/levels of "truth" (big, universal, truth versus, say, little and individual truth (not to be confused with perception). Whether or not something can be true without there absolutely being evidence would, I think, depend on the type/level of "truth" but also on the type/level of evidence required/expected. Smaller-scale truth, smaller-scale evidence - yes, there can certainly be truth without evidence sometimes. Absolute proof is one thing. Evidence is another.
The other side to some kinds of evidence of some types of truth is that there can sometimes be plenty of evidence but someone is either not willing to look for it or look hard enough for it - or else someone doesn't recognize it (or maybe even want to recognize it) when it is right there in front of them.