Dark matter interacts with light in the same way as a black hole does. They both have mass and therefore both bend space (and light passing through that space) around them.
It's already known that what we call dark matter in some contexts (e.g. the mass that holds galaxies together) is at least partly made of black holes. We just don't know if black holes account for 100% or 1% of the dark matter that we believe exists in a typical galaxy.
They’ve been both predicted and observed. Dark matter is a conjectural solution for an anomaly in the rotational speed of galaxies across their discs. In my opinion, it’s almost certainly a bodge, and if the W boson has a different mass to that expected it could account for what we call dark matter, as the implications go far beyond just the additional mass - if the mass is off, then perhaps the nature of the weak force is misunderstood - for instance, perhaps the mass variance is driven by a hidden variable, and that in turn could account for what we regard as “dark” phenomena.