At this moment in time, no one knows. The Mueller team isn't leaking anything.
We know about media reports but not Mueller's team.
So when folks say things about what he is up to and whether he has a case to make, remember this point: they know nothing more than we do.
I was recently reviewing the comments of a Republican journalist whose opinion rested upon the fact that Mueller is not finding anything. That's all very well, but he doesn't know the central fact underlying his opinion. Which means the opinion is worthless.