Were Elijah and Elisha related

No they were not. Elisha was the son of Shaphat, and was anointed to become Elijah's attendant. (1 Kings 19:16) He would follow him and cover his needs, including pouring water over Elijah's hands whenever he needed to wash them. (2 Kings 3:11)

In addition, there was a point where Elisha referred to Elijah as "father" as he was leaving to parts unknown. (2 Kings 2:12) This is because he was a close mentor, and viewed him as a father figure. This is also why he asked for a "double portion" of Jehovah's spirit from him (2 Kings 2:9); a phrasing that could be used when a firstborn son is being given an inheritance.

(New World Translation of the Holy Scriptures)