Can I claim my nephews who have ITIN's but live in Mexico, I live in the US and support them the whole year?

[georgesT]

Yes, you can if you provide more than half of his support!

You can claim a child, relative, friend, fiancé (etc.) as a dependent on your 2017 taxes as long as you meet IRS requirements.

See the following answer to FAQ on dependent eligibility:

https://ttlc.intuit.com/replies/5187060