No it doesn’t. “American Graffiti” came out in August of 1973. “Happy Days” premiered in January 1974.
Richie Cunningham and his family were introduced in a segment of “Love, American Style” in February 1972, which was later developed into “Happy Days”.
It’s coincidental that Ron Howard starred as Richie Cunningham in the television segment and as one of the stars of “American Graffiti”, but there is no doubt that his work in the latter helped him get the role in “Happy Days” and that the popularity of the movie helped Garry Marshall get the green light for the television series.
Correct.