Advertising drama “Mad Men,” facing a night of stiff competition on cable television, drew 2.3 million viewers to the premiere of its seventh and final season, network AMC said on Monday. Sunday’s hourlong episode was unable to match the 3.4 million that watched its sixth season premiere last year, according to data compiled by Nielsen and released by AMC. The episode faced off against MTV’s annual celebrity-filled movie awards show aimed at younger audiences.