This is, in fact, part of the support for Dark Matter, both with galaxies (the amount of lensing requires the galaxy to include a lot of Dark Matter) and between galaxies, where other lensing effects occur that can only be explained by filaments of Dark Matter between galaxies and galaxy clusters.
This is a great podcast, with episode 6 concentrating specifically on Dark Matter and the evidence for it: https://podcasts.apple.com/us/podcast/crash-course-pods-the-...
I wasn't saying, as a layman, that this is evidence for Dark Matter. I'm saying that the current thinking in astrophysics is that this is evidence for Dark Matter. Katie Mack, the astrophysicist in the podcast I linked, is a reknowned expert, and discusses how running the numbers on exactly these things provides evidence for Dark Matter, and how alternatives fail.
then she is being misleading, at best. To date no observed galaxies (versus galaxy clusters) have had the arrangement (as is in this image) wherein the galaxy is so perfectly in line with a background galaxy and close enough to estimate the rotation curves (and the background galaxy is of the right disposition to know if dark matter halos extend beyond the galaxy and estimate by how much space). Without both those factors it's really difficult to do a proper correlation of dark matter distribution around galaxies and the observed light bending.
no. you can't say it's evidence for dark matter versus any given other theory until after you have computed the expected metrics created by any alternative theory.
in any case, you can't say it's support for dark matter in this specific case without actually running the numbers (what are the rotational speeds and what is the bending curvature)
dark matter halos must have a somewhat specific distribution that goes beyond the perimeter of the visible galaxy itself.
however the more that i think about it this example is likely to be unhelpful. the closer galaxy looks elliptical and most dense elliptical galaxies "have no dark matter" (in basic MOND this is a phenomenon that falls out if the gravity law). We'd really need lensing from a more "normal" looking galaxy.