NOT need to pay USA tax in China. However, once she received the money here she has to pay the gift tax by herself or ask her parents to pay for her. Just like you go back to China, your friend give a gift to you valued more than the exclusion  by the custom. If you declair it, you have to pay the tax. If you do not but are lucky enough, you are absolutely fine, though not legal. If you get caught, you know the picture.