If they are currently valued at $1300 each with a private company valuation of $1B that means: You have to pay $1300 per share to acquire them and have no ability to sell them.

If the company goes public or acquired the company will have to be valued more than $1B for the options to be worth anything to you.

Honestly you shouldn't ever consider options to be worth anything more than the paper they're printed on until an IPO or acquisition.

Options (before IPO) are mainly a gimmick by management to keep people from jumping ship (they are typically dependent on continued employment). They cost the company virtually nothing. After IPO they have easily determined value.