It depends what you mean. Usually this sentence means that someone has not given someone (a teacher or boss) the work they were supposed to do. If you mean you haven't seen the person (not the work) it would make more sense to use " I have seen nothing OF you so far" instead.

Эдуард 's sentence has a double negative,( haven't seen nothing) so that would also be incorrect. However you could use "I haven't seen anything of you in a long time" or " I haven't seen you in a long time".

That would be correct if you were talking about something like work or school and the person had not done their portion of the work. If you mean thst you haven't seen someone in awhile, it would be better to say something like: "I haven't heard from you in awhile" / "I haven't seen you in a long time." Etc.

I am not sure, but I believe that it is: I haven't seen nothing of you since a long time. I think it is better by this way, I am not sure.