Como dizer "cinéfilo" em inglês

O fato que uma palavara está no dicionário nao quer dizer que se usa muito. Cinephile é um exemplo disto.

Movie/film - goer/lover/buff ?
Movie and film are used interchangeably. Another word also commonly heard in informal situations is "flick" (plural: flicks). The first movies/films had lighting problems and would "flicker" on the screen. "Flick" was soon adopted as a slang term for movies/films. Even today we have "Netflix" (net = internet, flix = movies/films/flicks).

A "goer" goes to the movies. If you watch movies on TV, technically you are not a "goer". If you walk or take transportation to see a movie, you are a "goer".

A "lover" loves. Need I say more?

A "buff" is someone with knowledge, interest, enthusiasm. If you can name five movies with Antonio Fagundes, you are probably a movie buff. A movie buff knows actors, directors, plots, differences in styles, etc. If you can tell us five things in common with O Lampiao and Maria Bonita of the Brazilian Northeast and Bonnie and Clyde of the USA's South, you are probably a history buff. A history buff knows dates, names of battles, types of uniforms, etc. If your favorite vacation is going to the Vale dos Vinhedos, you are probably a wine buff (or an alcoholic).

As you can see, it is easy (but not required) to be a movie buff, a film goer, and a cinema lover at the same time. The main difference. I believe, is that the buff studies, reads, compares, etc. His/her interest is active, not passive.

I hope these thoughts have been of help.