SANTIAGO — National Amusements has bowed Chile’s biggest multiplex, a Santiago 14-screener, in an intensifying battle for the No. 5 Latino B.O. arena.Later this month, Cinemark and local partner Conate will inaugurate a 12-plex, also in the capital, directly opposite an eight-plex operated by Hoyts. That will bring Santiago’s plex count to nine, with 78 screens. Before the year is out, Cinemark plans to add six screens to an existing six-plex, build two further Santiago hardtops (18 screens), and construct another four venues (26 screens) in the provinces. Not to be outdone, Hoyts is plotting a 20-screener for the La Reina district of the capital to open its doors in March 1999. Santiago has about 5 million inhabitants.