I have audio from a video where one microphone of five is quieter than the others. Is there a way I can do something like a reverse noise removal where I can profile the mic and amplify it? 
You have a video with five separate sound tracks? If what you really have is a video with five tracks mixed into one stereo or mono track, than you’re stuck. We can’t split a mixed recording back out into individual performers.
Some people have gotten relief with the compression tools. Effect > Compressor. That will make the regular parts of the show dense and loud in the hopes the low volume microphone comes up a little.
The profile for a high quality microphone is “everything.” That’s the problem. There is no good way to recognize one voice in a field of many. Or, more accurately, no way that can produce theater. There are some techniques and tools that can split parts of a show, but they can sound like a bad cellphone call, not announcing or performing.
Koz
Is there a way I can do something like a reverse noise removal where I can profile the mic and amplify it?
No. If you have 5 mixed channels, you can’t un-mix a recording.
Compression (the compressor effect) may help to some extent because it pushes everything toward the same volume. You’ll have to experiment with the compressor as there are several settings and ever situation is different. The limiter effect is a special kind of compression and you can try that too. But, compression won’t help much if several sounds are happening at the same time (because the sounds can’t be isolated or un-mixed).
There is one far out there hope. Each time the low performer speaks, are they by themselves? Always? If so, you can use the envelope tool and reduce the volume all the rest of the time and make them match the low microphone. Then bring everything up.
http://manual.audacityteam.org/o/man/envelope_tool.html
That will die if the room was noisy or the performers liked to talk over each other. Or both.
Koz