if you're asking about the express entry visa, then you need to post this question to the express entry board on this forum. more than likely, your nephew is not eligible to be sponsored through family class, so this board will not be relevant to your situation.
From a previous post, your nephew is 16 years old. You can try for a study permit with you as a custodian. Note that you will need to show proof of funds for his tuition and board; I believe tuition alone is about $13 000/year.