How to backup the vertica data to Amazon S3?

Yes, vbr supports backup to S3. Refer this doc page for help: https://www.vertica.com/docs/latest/HTML/Content/Authoring/AdministratorsGuide/BackupRestore/CreatingBackupsonAmazonS3.htm
Basically, you'll need to create a config file (here's an example) that points to an S3 Bucket. Once you've configured that, login as dbadmin and then:

vbr -t init -c config.ini
vbr -t backup -c config.ini