[SalesForce] Custom Object is not visible in Profile Tab Setting for System Admin

The System Administrator profile needs to be included in the deployment along with the custom fields and objects included. If it is not it will not automatically have access to the new fields created by the deployment.

In the short term you can either manually change the System Administrator profile in the target Org to give access to the fields or else redo the deployment including the System Administrator profile.

You can also depending on the tool you are using include just the specific permissions for these fields rather than the complete profile.

This previous question and answer may be helpful.

You cannot edit the standard profiles in any org. You do have two options however:

1. Clone the profile and add the necessary permissions
2. Create a permission set and apply it to users who require the desired access