This is a case of: It depends on the question and even then the answers wouldn't be the same. Why? Both are statements and in a sense don't reflect a real life conversational response when the subject and predicate are already implied; only the object of the question is required for a response. So it depends on the question if you are expected to make a statement out of your response.
EX. How long have you been living in New York?
TEFL answer: I have been living in New York since April.
Objective answer: Since April. /or Since last April.
EX. How long have you lived in New York?
TEFL answer: I have lived in New York since April.
Objective answer: Since April. /or Since last April.
Any teacher would beable to accept both as a statement. A computer administrated test: with test errors and out of context questions, questions that have nothing to do with TEFL and are basically TOEIC questions in disquise slipped into a TEFL test with 2 correct possible answers, one being more favored by the author of the test; is going to be unforgiving regardless of your English ability. So don't worry too much.
If your going to be answering a TEFL question; give them what they want for the sake of your test score. A statement using either tense stlye correctly.
If your going to be meeting people and making friends; answer in the objective so you don't sound like a casette taped played in ESL classrooms.
But seriously, either is fine if you are making a statement to someone first. The words 'lived' and 'been living' give the same meaning in the context of I as the subject; in relation to the preposition of time.
Translation: YES BOTH ARE OK!