The more RAM you have the more RAM apps uses, the diference between 8/16/32 is barely notciable, at the least when I saw those benchmarks. What you should be aiming for when talking about RAM is speed, and you CPU supports 3200mhz, you should get you hands on 2x4 3200MHZ or 2x8 3200MHZ pieces, make sure to install them propely so they can run on dual-channel. And no, getting those setting would not improve you gameing performance that much.
For gaming I go with this priority order: CPU > GPU > SSD (Loading time) > RAM.