The boy faces charges of aggravated criminal assault and manufacturing and disseminating child pornography. He was not named because of his age.
The girl was allegedly assaulted by five or six males last month.
Around 40 people were said to have been watching the stream at one point but nobody reported the incident to police.
A teenager had alerted a relative of the girl's, Reginald King, to the assault.
"There were adults who saw this. None of them had the wherewithal to say, 'Hey, I gotta call someone'," Mr King said.