Is loki related to thor

Officially, not in the least bit. Loki is Odin's blood brother, which is not a REAL family relation. Thor is Odin's son. However, there is some speculation that Lothur, Odin's brother mentioned along side Hoenir, might be an earlier version of Loki. In which case, Loki would be Thor's uncle. Of course, there is not the least bit of hard evidence that points to this, just circumstantial.