Bill Gates can gift you all his money and you wouldn't owe gift tax. Gift tax is on the donor not the recipient so it is never taxable to receive. For donors the annual federal gift tax exclusion allows you to give away up to $14,000 in 2014 to as many people as you wish without those gifts counting against your $5.34 million lifetime exemption. Taxable Gifts over $14,000 require a gift tax return but no tax is due until the lifetime exemption is exhausted.
Only two states, Connecticut and Minnesota, impose their own gift tax. Connecticut gift tax is owed when the value of all taxable gifts made by a resident since 2005 (not counting out-of-state real estate) reaches $2 million. Minnesota has a $1 million gift tax exemption.
So no gift tax is owed until a donor exhausts the $5.34 million dollar exclusion. Very few people ever need to pay federal gift tax.