Hi Avantika !
If you are planning for research , dont worry , gap year wont create any hurdle there. BHU offers a good syllabus , however , not much about the faculty is mentioned on their website. Since , I have not heard anything good about BHU's economics program , I won't give a thumbs up to the choice of joining BHU.
People fear gap year , however there is nothing to worry about it at all , provided you use that time efficiently. Go for a job , join some NGO , work on yourself , learn softwares , work under any academician , give time to your hobbies , focus on your goal , and last but not the least introspect. Just make sure , that if god forbidden , you do not make it to the top institutes , you do not regret this one year. Be a little foresighted , and equip yourself with enough knowledge and opportunities , so that in case of any failure , you have something in your hands. Good Luck !! :-D
"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."