It depends on what you mean by "populate". You can set up a system that copies data in to fields in your current record, or it can simply use fields from the related table to display the current values in that record.
As far as I know, the fact that the records are from external tables via ODBC does not change this basic set up. Whether you copy or just display the data requires a valid relationship based on the Job# field.
Here's a link you can look at to learn more: Auto Fill
When I type in the job name I want it to (fill-in other fields that relate in our ERP system) what ever value that is in the ERP system in the above fields for.
Customer Name, CSR, SalesPerson
Please read the link I posted. It addresses both options.
And what you describe can be done with both of the two methods I describe in that link. The difference is in what happens when data in the original table is modified. With one option, the changes automatically update what you see in your layouts and reports. With the other, they do not. Both approaches have their uses as sometimes a "snapshot" of the values that were current at the time the data was looked up is what you want and in other cases you always want the most recent version of the data to always appear.