Complex sentence: He got his big break in 1954, when he was hired as the male vocalist for with Count Basie Orchestra, 1954 through 1961, garnering some of the best exposure a blues and jazz singer could have.
Split into simpler sentences: He got his big break in 1954, when he was hired as the male vocalist for with Count Basie Orchestra. He remained with Basie until 1961, garnering some of the best exposure a blues and jazz singer could have.