Yes, Clay tables have a row limit. The current limit is 50,000 rows per table.
Additionally, each table in Clay has a column limit of 70 columns. Of these columns, up to 30 can be action or integration columns. If you implement a waterfall, this integration column limit will be raised to 40.
If you need to process larger volumes of data, you might want to explore features like row formatting or sandbox mode depending on your specific needs.