If things work out during your PhD, that’s not simply luck. You have to work for it. If you get the most fantastic results or the brightest ideas they come to you only through effort.
Which means that when you get to submission and then the viva, it’s not simply luck. You HAVE worked for it. The end result of a good thesis and a good candidate for the viva is due to your effort.
You’re fortunate, not lucky. If your hard work has produced results this far then what would stop your fortune continuing to the viva?