You said the person is a dependent. That changes things.
Assuming that is his only income, he must file a tax return if his unearned is over $1050.
https://www.irs.gov/publications/p17#en_US_2017_publink1000170430
From what I can see, the Alaska PFD was $1100, which would mean he is required to file a tax return. Unless he was a full-time student, Form 8814 can not be used, so he needs to file his own tax return.
