In this sentence, das is not an article, but a demonstrative pronoun (Demonstrativpronomen). It refers to the verbal phrase ins Kino gehen.
While diese[r,s] ('this') and jene[r,s] ('that') usually refer to real things and are somewhat emphasizing, der/die/das often refer to things from speech and are less emphasizing. There is no complete English equivalent, however it matches closely French cela/ça and Italian ciò, for example.
Der and die can also be used as demonstrative pronouns for nouns with the respective gender. Verbal phrases, however, are always refered to by neuter das.