Is there a upper limit to the number of values this variable can contain? AFAIK, QlikView won't be able to dynamically create text box objects for you, but if there is an upper limit, you might be able to create (20-30 text boxes) and conditionally hide show them based on the count of numbers within your variable.
You could count the number of values with: substringcount(YourExpression, 'YourDelimiter') + 1 and pick with: subfield(YourExpression, 'YourDelimiter', n) the appropriate values and use also the count as condition to show the textboxes.
no, not dynamically else like mentioned from you above it needs to create many objects in the forefront. But will be a table-chart used for this it could be dynamically (the layout-options are restricted then compared with many textboxes but it might be sufficient).