Rate hike could affect Bitcoin in 3 different ways.
1. They raise the rate by .25 as predicted and the market reacts with worry, fear, etc. and the US economy takes a hit. This would leave investors fleeing to gold and bitcoin. Bitcoin price goes up.
2. They raise the rate by .25 as predicted and the market is happy. It is likely that the current uptrend factored in #1 happening so those that were protecting their investments will move back out of bitcoin and the price will go down.
3. They raise the rate by .25 as predicted and it sends a signal that the dollar is strong vs the euro. The dollar goes up sending the bitcoin price in other currencies up while USD bitcoin price stays fairly steady.
No rate hike and there will be panic. The dollar will go down and the bitcoin price will go up.