Beatles were previously demigods

Whether Prabhupada stated that the Beatles were previously demigods is not really relevant. But Prabhupada did acknowledge that demigods would be queuing up to take birth in the movement. Look at this exchange on June 9/76.

Ramesvara: Devotees once told me you said that the demigods like this movement very much so that they're standing in line to take their birth in the Krishna consciousness movement.

Prabhupada: Yes. They like to come here on this planet. Of course, one can never be sure who a devotee really is, therefore the injunction of sastra is to always glorify the Vaishnavas.