Google changes this often and I'm having a hard time finding it in the GA documentation.
What are the limits for custom variables and advanced segments?
Are they specified at the account, property, or profile levels in Google Analytics?
The limitations to your question are as follows:
I hope this answers your question completely. Best wishes!
Take a look at this - Google Analytics Limits. I work as a technical analyst at an analytics agency and this is something very similar to what we use as reference.
Custom Variable Slots