Only General Available RHEL major releases will be examined.
There will not be exams related to beta releases.
Jan Gerrit Kootstra
Thank you i got email reply from redhat
12:18 (1 hour ago)
If you took RHCSA on RHEL 7 then your RHCSA should say RHEL 7 under "Technologies Used" section.
If you want to have RHEL 8, you need to take RHCSA on RHEL 8. It would still be the same RHCSA certificate though, therefore I don't think it makes much sense unless you have money to spare for the exam.