Will boats be able to move on river tiles, as historically alot of ports where adjecent to a river and not the sea or ocean. 

It has been confirmed that boats will only be able to travel on sea tiles.
Rivers give yield bonuses and allow your units to travel faster along them, but not ship units. At least as of now.

Thank you 

Ananashi wrote:

Rivers allow your units to travel faster along them, ...

That's excellent and reflects a major impact that waterways had on the development of societies. Like how goods in the American midwest might be shipped all the way down the mississippi to the Gulf of Mexico and then shipped up the East Coast to reach New England.