He's what called a "Clochard". It's a particular type of homeless person specific to French culture. He chose to live on the street on purpose, and gets donations from the local population. He probably gets small food donations from the local markets and those protein cans from shopkeepers in his neighborhood, in exchange he probably does a small neighborhood chore like trash or keeps an eye out at night and entertains tourists during the day, everyone in his neighborhood must know him by name.

He explains in the video that he'd rather live in the street and force himself to live rather than sit in a government appointed small boxlike apartment where he'd probably go nuts and back on drugs, which he battled most of his early life.