Hi. Not yet. We are working on a field type though that would allow for something similar. Actually the field type we were working on would be a configurable datagrid where you can allow for so many entries and the user can keep clicking the Plus character etc...
For example you specify the columns would be 'First Name', 'Last Name', 'Relationship' in a datagrid field type called 'Depdendents'. This would allow the user to keep clicking a plus character for adding dependents etc... Is this sort of what you are looking for?
Now, you can't do exactly what you specified but you could do something similar. You could create a dropdownlist (not textbox with an unlimited X value) and based on that dropdownlist you can have certain hidden fields appear etc... So for example the dropdownlist is 1 then just show 1 as the affected fields in the event. if the value is two display the affected fields Textbox 1 and Textbox 2 for the question event etc. If they chose 5 then 'un-hide' 5 textbox fields etc...
-Chad