i know that ''Ποιος'' means ''who''. İn which situations we can use ''Ποιος'' like in this question for example ''which'' or ''what''? İs it related with the gender of the noun?
Ποιος/ποια/ποιο are used for both 'who' and 'which one'. Τι is used to literally ask 'What is this?'
Saying "Τι είναι αυτός ο δρόμος;" would prompted someone to reply "What do you mean 'what is it'? Do you mean is it a street, a boulevard, an avenue..?" :)