What countries are Eligible for Asylee visas, and what do you need to prove, also can one apply for it even if you have been in the USA for a long time?
Anyone can apply for asylum. One can apply for asylum within one year of entering the US. There are a few exceptions to the one year filing deadline.
I have been in the states for 5 years now, will that effect the process?
You will need to prove to USCIS's satisfaction that circumstances in your COP have changed drastically after your one year was up in the US. This will be on top of the burden of proof that your life is in danger if you move back to your COP. What COP are we talking about here?
I am originally from South Africa, and that country is going downhill very fast
"Going downhill very fast" is not a basis for asylum. You need established proof that you face persecution and/or death if you are back in South Africa. Countries like New Zealand, Australia and Canada have points based immigration for professionals. Did you consider these as alternatives?