How exactly is the West Bank centered Palestinian Authority supposed to "take care" of Hamas in Gaza, when they are separated by many miles of desert occupied by Israeli forces? Are you suggesting that Israel open up a corridor so the PA can go fight Hamas? Please feel free to refer to a map of the region in question before answering.
The PA needs to send a team to Gaza. Israel would certainly make sure they got there safely. There are ways to do this. The PA should also use the assets they have in Gaza to get the true story out.
Hamas is not a Palestinian group. If Palestinian leaders told those in Gaza not to help or trust Hamas, things would also change.
If it is as you say it is, there is no hope for Gaza. Hamas' #1 through #100 (at least) goals are to rid the world of Israel and damn anyone who gets in their way.