I know it was on HBO, showtime, VHS in the 80s but I don't think it had any kind of mass following until TBS/TNT got exclusive TV rights in the early 90s, starting showing it every christmas day and the annual all-day marathon in late 90s. That's when I remember it just blowing up with ralphie shirts, christmas ornaments and leg lamps everywhere.

edit: https://theretronetwork.com/a-brief-history-of-the-24-hours-of-a-christmas-story-marathon/