my gate score was 614 in gate 2018.what is my chances for iits?my branch is civil.

Hello Rohit, Your chances of getting into IITs totally depends upon their admission cut offs this year, and the factors that affect those cut offs are as follows:
1.  Number of candidates who appeared for the entrance examination.
2. Number of seats that a college has department wise.
3. Difficulty of the examination ( GATE 2019 )
4. Category of a candidate ( reserved/unreserved)
5. Reputation of the Institute.
6. Previous year's cut off patterns.

So, I can help you with the last point, i.e., the cut off patterns of last year. With those cut offs you can actually evaluate your chances of getting into a particular IIT. And can expect this year's cut off trends.
1. IIT Delhi
https://engineering.careers360.com/articles/gate-cutoff-for-iit-delhi
2. IIT Madras
https://engineering.careers360.com/articles/gate-cutoff-for-iit-madras
3. IIT Bombay
https://engineering.careers360.com/articles/gate-cutoff-for-iit-bombay
According to this cut off you might get admission in IIT Bombay in the specialisation- remote sensing. (If you are from general category)
4. IIT Kharagpur
https://engineering.careers360.com/articles/gate-cutoff-for-iit-kharagpur
5. IIT Guwahati
https://engineering.careers360.com/articles/gate-cutoff-iit-guwahati
Here, if you are from unreserved category you can get admission into water resources engineering.
6. IIT Kanpur
https://engineering.careers360.com/articles/gate-cutoff-for-iit-kanpur
7. IIT Roorkee
https://engineering.careers360.com/articles/gate-cutoff-for-iit-roorkee
8. IIT Hyderabad
https://engineering.careers360.com/articles/gate-cutoff-for-iit-hyderabad
You can get admission only in one specialisation here, only if you are from reserved category.
9. IIT Indore
https://engineering.careers360.com/articles/gate-cutoff-for-iit-indore
10. IIT BHU
https://engineering.careers360.com/articles/gate-cutoff-for-iit-bhu
11. IIT Gandhinagar
https://engineering.careers360.com/articles/gate-cutoff-for-iit-gandhinagar
12. IIT Dhanbad
https://engineering.careers360.com/articles/gate-cutoff-for-iit-dhanbad

It is difficult to get admission into civil engineering, but there are a few specialisations you can go for.

And if you are seeking a more accurate prediction, you can check our college predictor and know which IIT you can get into. The link is given below:
http://bit.ly/2J9S0MN

All the best!
I hope this helps.