Evidence that irrefutably proves something is very strong evidence.

Evidence that kind of points towards something, but inconclusively, is weak evidence.

For example, if 100 witnesses saw the accused murder the victim, and they're all credible, and they tell corroborating stories, that's pretty strong evidence.

If 1 person thinks he saw the accused murder the victim, from the other side of a car park, but he has bad eyesight anyway and it was dark and raining, then that's weak evidence. It's not nothing, it's still evidence, but it is weak.

This seems to be equivalent to asking if there is any such thing as strength of evidence at all, and so yes, of course. The evidence that 100mg of cyanide will kill you is very strong, the evidence that seed oils cause inflammation is weak, even though there's a lot of it.

If you're bayesian.

Wouldn't that mean the quantity vs quality of conspiracies though?

Sort of.. at least there is in the scientific tradition.

Your theory predicting reality is generally weak evidence. It opens your theory to invalidation if the prediction fails, but does not rule out hypothetical alternative theories that also make the same prediction.

Theories aren't evidence at all, what could you mean by this?

A particular theory is a glue potentially connecting some number of observations. The observations + theory are evidence.

The reason that a messy pool of blood on the floor is evidence of violence is the theory that the blood came out of a person in a messy way.