Question

What role did the move of the capital to Constantinople play in the growth of the Byzantine Empire?

Answer 1

It made it the new center of the empire that Constantine inherited, strengthening the East via commerce and trade and pushing Rome into the backdrop.

As great as the city of Rome was in that time, Constantinople was at the very front of where all of the excitement was in the East as a major port of call for trade. It's one of the reasons why the natural harbor that split Constantinople on was referred to as the "Golden Horn" because of all of the wealth flowing into the city.