In the Web Portal, you can go to Forms > Submitted Forms, and in the list there is a column called Job ID. You can see here what forms and jobs are connected. This is a column that can be added to custom submitted forms tabs as well.
You can also see this if you have the form open, by clicking on the Details tab.
If you open the job view, you can also see if there is a saved or submitted form ID connected to it and open the form from there.
