Does the recipient has to pay tax, or report receiving the Bitcoin?
receiving: US, sending: China.
Edit: receiving gift.
I am assuming the money is a gift.
For intangible gifts from foreign persons, the gift is reportable if it is over $100,000 in fair market value. If the amount is less than this, the gift does not have to be reported. If the gift is coming from a foreign corporation or organization, any amount over about $15,000 is reportable. The IRS has a web page with guidance on this form. Note that payments for tuition or medical expenses are not considered gifts or income and do not have to be reported.
Gifts from foreign persons are not considered income and are not subject to income tax.
Depends on jurisdiction, but generally: you pay tax not on cash income, but on value received. So, in case of someone gifting you bitcoin you the local tax situation applies SIMILAR TO SOMEONE GIFTING YOU MONEY - with the value of the bitcoin (as per exchanges) at the time of the gift.
This is in line with normal tax laws, similar to someone gifting you a bar of gold.
Depending on value a gift tax has to be paid. Between US and China it is time to ask tax advisors.