This line is often misquoted as "If you build it, they will come". But in the film it's definitely "he" – "he" being Shoeless Joe Jackson, the legendary but disgraced baseball player. Some observers have interpreted the film as an allegory on the second coming of Jesus: if we have faith, he will return.
I've also seen the line attributed to James Earl Jones, who plays Terence Mann in the film. (Kevin Costner's character is based on W. P. Kinsella, the author of the book on which the film was based; Terence Mann is a fellow author.) But this line is not spoken by the James Earl Jones character but by a disembodied voice, which as far as I can ascertain is not credited.
© Haydn Thompson 2017