Though he hasn't had anything like a hit since ''Shanghai Breezes'' went to No. 31 in 1982 or a real smash since ''Calypso'' peaked at No. 2 in 1975 pop-rocker John Denver's influence lives on. Or so was the contention of a copyright infringement suit that began when an employee of Cherry Hill, Denver's music publisher, heard a New Order song on the radio. Cherry Hill's lawyers claimed that the British dance quartet's 1989 song ''Run'' borrows considerably from Denver's ''Leaving on a Jet Plane,'' which Peter, Paul & Mary rode to No. 1 way back in 1969. New Order's lawyers eventually allowed that there had been some ''clearly inadvertent'' infringement and agreed to pay a standard royalty to Cherry Hill. Denver, a spokesman says, has been unaware of the suit.