Assuming that you're going to run full backup on weekly basis, the number of restore points stored at each point in time will vary
In your case, this number will be somewhere between 7 at 13 with two of restore points being full backup. For full backup you can use 50% as a data reduction ratio (compression + dedupe), because typically you won't see ratios less than that. So, the corresponding full backup should be approximately equal to 1.7 TB.
As to increments, they are equal to 5-10% size of full backup, depending mostly on amount of changes produced between backup cycles. For highly transactional VMs, such as Exchange, SQL, etc., the number can be up to 15-30% due to transaction logs activity.
Taking all of this numbers into account, you can roughly estimate the amount of space needed in your scenario.