does being elligible for jee advanced mean that at the time of jee main counselling we would be having a rank less than 1.5 lakh.??/

Yes, only top 1.5 lakh students would be eligible for jee advance.

It is a common modus operandi of the test and leading institutions that top 1.5 lakh students will be given opportunity to pursue admission, you simply keep an eye on the official weblinks of IITs or NITs and keep on checking the current position of counselling rounds so that you may find your atsture there,,,if you could not crack it at IITs etc evemn then don’t give up as there are certain other renowned institutions where you can seek admission and live upto your dream of being an engineer, to my mind you may visit at – Malaviya NAtional inst of Tech, Jaipur,......Banasthali Uni, Banasthali......Lovely Professional Uni, Phagwara,......College of Engg and TEch, Bhubhneshwar