Radio Buttons Not Displaying

As Rob has pointed out your problem is being caused by a script trying to replace your radio buttons, after examining a couple of your themes js files I have narrowed it down to the uniform plugin contained in your themes libraries.js file and the corresponding styles contained in button.css

The uniform plugin masks standard form inputs with custom themed inputs by injecting and modifying the html code as the page loads which is why you have extra span tags surrounding the radio inputs and why they have been hidden.

From what I can tell though it looks like the job isn't being done properly for the radio buttons, yet it is for the check boxes. It looks like there may be a couple of styles missing from button.css because the following styles are all adjusting the background image that is supposed to form your radio button but I can't find a rule that is setting the background image. You need to speak to whoever created your theme and find out why that is missing.

div.radio span {
  height: 18px;
  width: 18px;
  background-position: 0 -279px;
}

div.radio:active span, div.radio.active span {
  background-position: -18px -279px;
}

div.radio.focus span, div.radio:hover span {
  background-position: -36px -279px;
}

div.radio.focus:active span, div.radio:active:hover span, div.radio.active:hover span, div.radio.active.focus span {
  background-position: -54px -279px;
}

div.radio span.checked {
  background-position: -72px -279px;
}

div.radio:active span.checked, div.radio.active span.checked {
  background-position: -90px -279px;
}

div.radio.focus span.checked, div.radio:hover span.checked {
  background-position: -108px -279px;
}

div.radio.focus:active span.checked, div.radio:hover:active span.checked, div.radio.focus.active span.checked, div.radio.active:hover span.checked {
  background-position: -126px -279px;
}

div.radio.disabled span, div.radio.disabled:active span, div.radio.disabled.active span {
  background-position: -144px -279px;
}

div.radio.disabled span.checked, div.radio.disabled:active span.checked, div.radio.disabled.active span.checked {
  background-position: -162px -279px;
}

The button.css style sheet is part of the problem, the uniform plugin that is injecting the extra code and hiding the gravity forms radio buttons is the second function in the libraries.js file

It's the uniform script from the libraries.js file that is injecting the opacity:0 style. If you comment out or remove the second function from that file and then try viewing the form the standard radio buttons should now be visible