I think there's no limit. How many do you need?
I was trying to add 10K, but I stopped it at about 4000.
In Illustrator no layer limit is known.
Are you really talking about layers or about the total number of objects/paths?
It's limited by the amount of RAM. Too many objects and you will get in trouble. If you add effects and transparency into the calculation then there will be even more limits.
And there is a limit to the number of points on a path, that may lead to issues with imported files.
So if this is crucial to you, test it in advance.