Are commerce with informatics students (computer application) eligible for doing BCA?

Well yes maths is necessary but in few universities maths is not mandatory.

Mathematics is a compulsory subject in 12th for commerce students to to eligible for BCA.

Yes, commerce students can pursue BCA even after being from non-mathematical background. Many universities provide admission to such students/candidates. Just look for that university and college, as you've already studied computer Science in your +2, BCA will be relatively easy for you. If you want

Yes, you are eligible for the same, as in BCA you only have to do the coding that has no relation with any other subject.

Yes, commerce students can pursue BCA even after being from non-mathematical background. Many universities provide admission to such students/candidates. Just look for that university and college. As you've already studied computer Science in your +2, BCA will be relatively easy for you. If you want