I am preparing for Salesforce Revenue cloud consultant certification exam, is their any voucher available?

I' not aware of an exam voucher, but I do know that Salesforce is running a free retake promotion right now. Here is some info about it. 

https://help.salesforce.com/s/articleView?id=005460244&type=1

https://www.salesforceben.com/salesforce-exam-retake-policy-is-it-really-free/