Each button need not have a separate *variable* name used to create it.
I.E. you are creating one *new* button with the
       Button btn = new Button();
each time you go through the loop.  Just do all the work for that button
(using the "btn" variable) inside the loop.  Once you add it via the
Controls.Add statement, one new button is attached to the form.  When you
are done with the loop, you have created many new buttons, all via the
variable "btn" (which is different, conceptually, than the button's Name).

However, you may wish to clean up the buttons the next time through your
function (or, you can just let the gc collect them and it will call
Dispose()).  In the former case, you should/could save the buttons as you
create them, in an array (declared (as a variable) in the Form class you are
creating):

       List<Button> myButtons = null;

Then, just before you *enter* the loop:

       if (myButtons != null)
       {
           foreach (Button myButton in myButtons)
               myButton.Dispose();
       }
       myButtons = new List<Button>(10);

then inside the loop, in addition to your existing statements, place:
               myButtons.Add(btn);

If you want to do something else with the buttons, outside the loop
(although I don't know why you would), you can get at them via the
"myButtons" variable.