Paper in somebody else's thesis
(note: I write this answer from a perspective in the biological/medical sciences, and norms about how to 'count' thesis work varies by field; however, in the fields I work in this sort of thesis where separate published or publishable papers are 'stapled together' is the norm)

It's great that your collaborator's colleagues are going to lengths to credit their work by citing their thesis.

However, a thesis is in some ways not a full publication, isn't really peer reviewed, etc.

You should publish the paper in a more conventional way if you want it to be cited by (and read by) the broader community. Your best bet would have been to do this when the work was prepared originally (and then the thesis would have cited as well as reproduced your collaboration).

No, you can't claim citations of their thesis as your citations, you didn't author their thesis and there is a lot of other content in there that is not yours.