Hey there, Gustavo
If you have lost access to the Microsoft Authenticator app and are unable to sign into your Rockstar account, please can you go through the recovery process by reaching out to Rockstar support here: https://support.rockstargames.com/request/account/trouble-signing-into-your-account/account-recovery
It will take you to a form where you will need to enter as much information as possible so the team can verify who you are.
If you have lost access to other accounts you had on the Authenticator app, if you have signed into your Microsoft account on the Authenticator app, it should have created a backup. This backup will be placed onto a new device when you download and sign into the Microsoft Authenticator app.
Hope this information helps,
Nathan