Dear Accountant,
If I were to give someone a large amount of money as a gift, do they have to pay tax on it? If so how much?
Thanks,
Alex.

No, the recipient doesn't pay, but the donor may owe. A person can give up to $13K per year without incurring a taxable event. There are also lifetime exclusions.

In some very isolated cases, the recipient MAY be required to pay the gift tax if, after filing the gift tax return, it is determined that the giver owes the gift tax but is NOT able to pay.

Otherwise, the giver is obligated to pay the tax.