wp cli is usually installed as just wp, but sometimes you may find it called wp-cli instead.
/path/to/wp-rocket-settings-backup.json is the exported json file from wp-rocket. Replace with the path and file name of the json file on your server or cluster.
$ wp package install --allow-root wp-media/wp-rocket-cli:trunk$ wp rocket import --file=/path/to/wp-rocket-settings-backup.json