Guys, I have to shoot 3 days of interviews with a Sony A7II and an A6000. Each day will last around 5 hours. I'm wondering how many batteries do I need for each camera.

I suppose it depends if you have access to an electrical socket where you can charge the empty batteries whilst you are still shooting. I use the A7s on two camera shoots and have 8 batteries, but on most shoots I take three chargers and start recharging the flat batteries while I keep shooting with fresh ones.

Worst case scenario, lets say I don't have access to outlets...would 8 batteries per camera hold for 5 hours?

I think 8 batteries would be OK for one camera over five hours, but I might buy a couple more just to feel safe... a lot of mine are third party non-Sony batteries and they last just as long as the originals. I work on the basis that one battery lasts around 40 minutes in the A7s (indoor shooting - may not last as long in cold climates)