Gabe, you have 9 or 10 nice little plants in that pot. Each one of them is going to need its own pot of at least the 30cm. size for them to continue growing to where you can harvest leaves regularly. They're going to get all tangled together at the roots, and run out of nutrients in that one pot very soon.
Each plant will grow to a foot or more in height, a nice little bush if you can pot them up properly and fertilize them. You'll have all the basil you want.
