I think these questions are duplicates.
MSO question: How many Stack Overflow accounts are banned from asking questions?
MSE question: What happens to folks who get question banned, by and large?
Are they duplicates?
If not, would linking the answer in the second link be a valid answer to the first question?
Well, they seem to be duplicates indeed. Usually you would close the one as duplicate of the other.
The problem is, we don't have cross-site duplicates. For meta you often want that, because an answer on the uber-meta can be a valid answer on a site-meta's question. (there must be a proposal lying around somewhere here, let me see... something like this one)
In this case, just comment with the link, or write a full answer and tell how it applies at this moment, for example.
I don't think they are duplicates. One question seems to want to find relevant data to what happens after users are banned, to possibly see if the banning system is working effectively or not or other reasons. And the other just seems to want to know a count or percentage of users that are currently banned from asking for curiosity's sake.
The meta.SO question's data request is not in the meta.SE answer. The answer does include helpful data but it didn't include a count or percentage of users that were currently banned from asking questions. It did include how many user hit the ban in the past 30 days, but didn't give any number to how many are currently banned from asking.
If not, would linking the answer in the second link be a valid answer to the first question?
No, a link is never a valid answer unless the hyperlink text is the answer. For example, if you linked like
then it's valid answer, but if you just did
then it is Not an Answer, and will likely be deleted if not edited to actually provide an answer that tells us something. See here for more info.
