I am super excited by this as it is both a big coup for GitLab (a lot of projects and developers) and a great leap forward for drupal.org tooling and workflow.
Wow they have 45k projects? I imagine a lot are dead/outdated modules, but even so it's a fair amount.
I would probably say that 15k are probably dead. But there is quite a lot of use of the top modules. And a lot of developers involved.