Passing variable to a page using Gravity Forms

So I've got a Gravity Form that allows a user to select a form and redirects on submit to a page containing that user-selected form. The first form has 10 options for the user, with therefore 10 conditional confirmations to 10 different pages. I'm using a redirect query string on the form confirmation to pass the user's selection as a variable ($document).

I'll eventually need to offer users 100 options, which will require 100 confirmations and 100 pages, plus a different form for each option.

Instead of building 100 pages, I'd like to build one page that dynamically loads the proper form based on user selection. I want the confirmation on the first form (where the user selects the desired form) to redirect to that dynamic page, passing the user's selection as the variable ($document).

I'll need to load that page using a template, and the (Genesis child theme) template for that dynamic page has this code:

add_action( 'genesis_loop', 'abc_custom_loop' );
function abc_custom_loop() {
    switch($document) {
        case "Blank":
            gravityform(11, false, false, false, '', false);
            break;
        case "Page 12":
            gravityform(12, false, false, false, '', false);
            break;
        case "Page 13":
            gravityform(13, false, false, false, '', false);
            break;
        case "Page 14":
            gravityform(14, false, false, false, '', false);
            break;
        case "Page 15":
            gravityform(15, false, false, false, '', false);
            break;
        case "Page 16":
            gravityform(16, false, false, false, '', false);
            break;
        case "Page 17":
            gravityform(17, false, false, false, '', false);
            break;
        case "Page 18":
            gravityform(18, false, false, false, '', false);
            break;
        case "Page 19":
            gravityform(19, false, false, false, '', false);
            break;
        case "Page 20":
            gravityform(20, false, false, false, '', false);
            break;
        default:
            gravityform(11, false, false, false, '', false);
    }
}

genesis();

but I can't get the page to load the correct form. Logs show the variable $document isn't being passed to the page, so the default form gets loaded each time, no matter what the user selects. Is there a better way to pass the variable?