Here's a calculator to figure out the number of images that can fit on various card sizes. The calculator doesn't have a 2TB setting, so you'll need to do a little math:
http://memorycardcalculator.com/index.html
Which camera? What's the resolution of the images? These variables must be known to provide a reasonably accurate answer.
Compression Level: Depending upon how the level of compression, you'll get more or less images on a hard drive.
I would suggest first determine the camera. Then look at the owner's manual for that camera. In the manual, it will usually have a section explaining the number of shots that can fit on any size of card.
Because of the unknowns within your question, it's not possible to provide an answer no matter how large the ball park.
However, I can give you some examples; after all there aren't a lot of resolution levels available.