audio between -60 to -50. can it be saved?

I shot a friends outside wedding but the audio dropped to -60 the second the lav mic was turned on. Is there a way to boost it up enough to sound decent?

Many ways to boost the gain, none will make it sound decent my guess. You're boosting the noise floor as well. You can then work on noise reduction but the results will likely be somewhat problematic.
You can turn up the gain any number of ways and if no single filter can do it, you can duplicate the track but it's not going to sound great.