Sometimes I use a half a can of olives for something and I just put the rest into a Lock & Lock container, in the refrigerator. That seems to buy a lot of time. Last time I believe it was a few weeks before I used the other half of the can.
I never thought of freezing olives. I just figured they would go to mush or something. Nice to hear that you can freeze them. If I were going to vacuum seal them, however, I would freeze them in a block with the liquid and THEN vacuum seal it.