Gizmodo thinks it will have at least 12GB RAM, but it sounds more like an educated guess than a confirmed fact:
replyhttps://gizmodo.com/ipad-mini-oled-a20-pro-chip-2000830541#:...
The 512GB option actually has a better chip with 1 more CPU core and twice the neural engine...
replyWhat does twice the "neural engine" get me?
replyFor about the same cost, I can get a used M5 chip with both a Neural Engine™ and GPU cores each with Neural Accelerators™