12,395 days.
How many times did Bill Murray relive Groundhog Day?
However, in a commentary special feature of the movie, director Harold Ramis said Phil relived the day for 10,000 years before later saying it was probably about 10 years. The movie itself never actually reveals that detail, however, Whatculture.com ran some numbers and revealed the number was likely over 12,000 days, which would come to roughly 33 years.
We see him relive Groundhog Day 38 times in the movie while another 414 days were mentioned in the film. Whatculture.com then used the theory that it takes 10,000 hours to master any one subject which brings his total to at least 12,395 days, assuming he mastered the piano, French poetry, and ice sculpting at different times.
https://www.wtaj.com/news/groundhog-day/things-you-might-not-know-about-groundhog-day-the-bill-murray-movie/