Most of Magento 2 database tables use the InnoDB storage engine.
It does not have a limitation for number of rows per a table.
But is does have a limitation for the maximum size for a table: it is 64 terrabytes:
The maximum tablespace size is four billion database pages (64TB). This is also the maximum size for a table.
http://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html