To become an Oracle DBA Engineer, you need to have a some technical and interpersonal skills. Here are the list of technical skills -
Knowledge about Database administration
Basic knowledge of operating systems
In-depth knowledge of Oracle database technologies
Strong understanding of SQL and PL/SQL programming languages
Troubleshooting and problem solving skills
Not only these skills you also requires softskills. In order to expertise all these skills it is better to go with instructor led training for that I would suggest you to take up this oracle rac certification training from Intellipaat. This program help you to become a certified professional with all the required skills.
Along with that have a look at this video on how Intellipaat helped Abhishek became an oracle dba engineer.