In the original JavaScript for this, we're HTML encoding the signature image and placing it in a custom HTML field. Because we want to grab this image on a different form, and because custom HTML fields don't have variables, you'll need to slightly modify the JavaScript on the form where you're capturing the signature so the HTML encoded version gets stored in a field.

So, add a single line field to the form (there are a couple versions of the original JavaScript floating around. If you're using the one where signatures are within a collection, you'll add the field to the collection) and give it the image CSS class.
 

Now modify the JavaScript a little bit. Find this function (again, depending on whether you're using signatures in collections this might look slightly different).

$('.donebutton').click(function () {
    var section = $(this).closest('.sigCollection');
    var sigdata = section.find('.signature').jSignature('getData');
    section.find('.sigdata textarea').val(htmlEncode(sigdata));
    var $img = $('<img class=imported></img>');
    $img.attr("src", section.find('.signature').jSignature('getData')).appendTo(section.find('.sigimage'));
    section.find('.sigGroup').remove(); //class added to the signature button and image custom HTML fields.
    section.find('.sigwarning').hide();
});

On the line that starts with section.find, update the selector so the line looks like this:

    section.find('.sigdata textarea, .image input').val(htmlEncode(sigdata));

This is putting the HTML encoded version of the image into the field you're going to reference on your second form.

Create the second form and add the field variable for the single line field you just created to it. In addition, create a custom HTML field with <div class="sigimage"></div> as its HTML content. On the CSS and JavaScript page, add the following code:

function htmlDecode(value) {
    return $('<div/>').html(value).text();
}
 
$(document).ready(function(){

    var sigvalue = $(this).find('.image input').val();
    var decoded = htmlDecode(sigvalue);
    var $img = $('<img class=imported></img>');
    $img.attr("src", decoded).appendTo($(this).find('.sigimage'));

});

That should do it. As a note, this doesn't work if the single line field is read-only, but you should be able to get that working with a little tinkering.