Colleges in Tripura

I would like to suggest you that do not go for NIT Agartala. NIT is a name that is just blindly followed in India. I know that a student of NIT has a good image for the spam of time from which he is selected to the time he completes his bachelors from a NIT. But speaking to the point there are only some good NIT , like NIT Trichy, NIT Tiruchirappalli, NIT Uttarakhand, NIT Delhi and some more. Not all of the are good. You will definately have a good name for the period of your college time but once you complete your college , you will have a tough time finding a good job. The placements at NIT Agartala are not good enough, but if you are happy with a package of 3 to 4 Lakhs after getting good marks and enough hard work , then only I think you should go to NIT Agartala.
Now comming to your question, the cut off marks will be around 140 to 170.

The M.A. in English is a postgraduate programme covering a wide range of English Language and Literature and Linguistics topics. Because Literature is such a broad topic, students are given a chance to choose electives and specialise in a field of their choice.
All schools and institutions have nearly identical eligibility requirements for M.A. in English courses. A few of the essential qualifying requirements to follow are listed below.
Students should earn a Bachelor's degree in English with a 45 per cent to 50 per cent aggregate grade point average or an equivalent CGPA.
After meeting the qualifying requirements, students must take an admission exam or be chosen on merit, depending on the institution or university: JNUEE, DUET, IPU CET, BHU PET, CUCET, AUCET, JNUEE, DUET, IPU CET, BHU PET, CUCET, AUCET. Also the cut off is around 20 closing CUET score

You may get seat in NIT Agartala , it depends on your category and branch preference. If you are an open category student them you cannot get any seat in any of the NITs whether it is gender neutral quota or female only quota.
It's possible that you get seat in EWS category or PWD category or OBC category or SC category or ST category that too it differs in gender neutral quota or female only quota.
Since you are category wise rank is 5105 you are eligible for some of the and IIITs and GFTIs in category reservation and gender neutral quota.
You won't get seat in NIT Agartala but you will get seat in IIIT Agartala in Computer science and engineering department.
You can check the college predictors using your rank and percentile so that you'll get a proper idea of colleges which you are eligible to get a seat and decide accordingly!!
Sure thing is that you cannot get a seat in NiT Agartala in any of the branch .
Better to go for IIIT Agartala , CSE if you are interested to join only in Agartala.
But in some cases you may get seat as you desired if you are Home State student for NIT Agartala( note: not always).