that's a misreading of what I wrote. I mean, the predictions made by the theory have been found to be true, not that the theory itself is ever proven to be true.
A scientist might make a hypothesis that suspect A is the murderer; the prediction would be that the murder weapon would be found in their house, the fingerprints match, blood types match. Upon search, the murder weapon was actually found, and fingerprints and blood types match.
A layman would say that finding the weapon converted the theory into a nearly certain fact.
A scientist would say that finding it pushed the hypothesis towards being a theory.