I was so excited that this month's Final Girl Film Club selection provided me with a reason to unearth my Bava box sets! Alas, as happens more often than not, I was all preparation and no follow-through when the deadline arrived, but I'll share below some comments I found about the inspiration this film had on the Friday the 13th series that I found in Crystal Lake Memories: The Complete History of Friday the 13th.
Sean Cunningham, executive producer, Friday the 13th:
Victor Miller, screenwriter, Friday the 13th:
Friday the 13th: Part 2
Ron Kurz, screenwriter, Friday the 13th Part 2
Also, an excellent explanation of the plot, from The Mario Bava Web Page.