Soufflés are not as tricky or fragile as you might think. There is lore built up around this—perhaps from an episode of I Love Lucy. But while most soufflés will easily survive a quick peak in the oven—why would you? Turn on your oven light if you need or want to see it in various stages of rising, but wait until the soufflé is due to come out of the oven to open the door—simply because you don’t want all the hot air in the oven to escape or the colder outside air to drop the oven temperature.
All of the above, by the way, is true for anything you cook in the oven: open the door only when needed to check on the progress – not just because you are curious to see how your cake, turkey, pot roast, or cookies look every few minutes!