The disk will be filled up once the total of all thinly provisioned disks reaches 1TB. You can create even 1000 thinly provisioned disks and they are going to work just fine on 1TB datastore as long as you don't actually STORE over 1TB of files on them.
Once again, you can allocate more than 1TB of space to as many virtual, thinly provisioned disks as you want, however you won't be able to store anything more than 1TB of actual data. Once you reach 1TB of data across all your thinly provisioned disks, your datastore will be filled up.
Did that answer your question? It's not the easiest task to understand what you're asking about - sorry.