Couturier-entrepreneur-theater producer Pierre Cardin, saying he feels like a cross between Cupid and a diplomat, has arranged a month-long engagement for the Russian rock musical "Juno and Avos" at New York's City Center in January. The rock opera, written in 1980 by dissident Soviet poet Andrei Vosnesensky, is based on a Russian sea captain's love affair with the daughter of the Spanish governor of San Francisco, circa 1800. Cardin says the production is costing "the eyes right out of my head. . . . but money is never any concern of mine. I just want to see more mutual Russian-American understanding. I don't think Americans know enough about the Russians." Cardin presented the Russian work in his Espace Cardin theater in Paris in 1983.