Hello Harish,
As far as the rank of your son is considered let me tell you it's a very good rank and he can easily get cse in SRM chennai. The cut offs as per the previous year trends does not goes below 12k so you can easily get that branch.
Although various factors are considered while deciding the cut offs like number of candidates appearing in the examination, number of vacant seats in college previous, years cut offs and difficulty level of the paper.
To get complete information you can check out the link given below-
https://engineering.careers360.com/articles/srmjeee-cutoff
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