Does a hole through small gauge wire affect current and voltage to the source?
Depends if you damaged the conductor inside or not.  If you've just pushed some stranded wire around not much will change.  If you've cut through 50% of the wire your safe current handling will go down as this section will be essentially a thinner conductor.  That will make it your likely failure point for large current.  If that's outside or exposed to moisture it could short to gnd and will likely corrode over time.

Let's say for example you've only left one thin strand of copper in there.  When the power starts flowing it will probably heat up burn and break the connection.  Same could be true if you have enough current and only half the wire.  

You could just cut it, splice it, and weather proof it to be on the safe side.