CSE in KIIT is better than IT in IEM, Kolkata. It offers better exposure to students. In terms of infrastructure, facilities, and placement, it is better as well. According to the recent placement highlights, the average CTC offered to CSE students is around INR 5 LPA. While the highest CTC offered this year was INR 12 LPA - 14 LPA. Companies such as Accenture, TCS, IBM, etc. take part in the campus recruitment of KIIT.
IT in IEM is better than a CSE in KIIT. Be it faculty, the quality of education, the student crowd, everything is much better than SRM, VIT, etc. (basically, any private institute). Don’t judge the institute by rankings, it often fails to depict the quality of an institute.
There are a few things about IEM that you should keep in mind before you decide.
Having said that, the decision entirely depends upon you. But I would insist that IEM is much better and would be a wiser choice than KIIT.