"Arthouse audiences" refers to people who enjoy watching independent or non-mainstream films that are often seen as more artistic and less commercial. Full definition
«The core [for this film] is the traditional older arthouse audience that are reachable through favorable reviews, advance screenings and print, online and social media advertising.» (deadline.com)
What a shame it didn't catch fire with arthouse audiences and award voters. (thefilmexperience.net)