Might not impact ollie power but it will impact stability in the air and on landing, flexibility (making grabs easier or harder depending on stance) and a bunch of other shit. Some guys like smaller stances for spinning too while others like wide for balance on rails. I like a wide stance for everything, just feels right. After 25 years I've tried just about everything and +15/-15, 23.5 is money for me.
edit - I find a wider stance gives you better style too.