All Perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as that of his family and all his companions.
If the orphan you are asking about is among the categories that are liable to receive Zakah as mentioned in Fatwa 88368 then you may pay your Zakah for his education. However, it is preferable to give it to him, or his guardian since he knows his necessities better.
See Fatwa 83451 to know the Islamic definition of an orphan and the permissibility of sponsoring him from Zakah if he is among those who are eligible to receive it.
As for giving Zakah to a brother, a sister or relatives and giving it in the form of gifts and the like, see Fataawa 89408 and 81892.
Allaah Knows best.