As per this article by the Washington Post he does:
Laita will give between $20 and $40 to people who are willing to tell their stories, he said. Those who are more at risk of being exposed, such as pimps, drug dealers or prostitutes, sometimes want more, costing him up to $100.
On any given day, up to eight people line up willing to share a personal history that Laita uses only his gut to check, he said.
“I am certain that not every dollar I’ve given to somebody on the street has been spent on a blanket or a tent or shoes. What I’m doing is not foolproof,” he said, considering his work to be a tool for awareness and education.
If he is claiming to not pay his subjects now, that is possible as this article was printed last year. But as the direct quote from Mark Laita states, he did, at one time, pay these people for their time.
Thank you for reading! :)