Both "Te Amo" and "Te Quiero" mean I love you. Te amo would be used with friends with no sexual connection, while Te Quiero would be used with somebody you do have a sexual connection with like a husband or boyfriend(wife, girlfriend).
Le / lo amo, pero, ¿me ha de amar él? / ¿me amará él? / ¿será que él me ame?In this sort of sentences, in which you express a doubt, the imperfect future indicative is used in Spanish.