Did Gautama Buddha know his path?
Possibly. For example, MN 4:

Before my Awakening, when I was still an unawakened Bodhisatta, the
thought occurred to me ... If anyone, when speaking rightly, were to say: 'a being not subject to delusion has appeared in the world for the benefit &amp; happiness of many, out of
sympathy for the world, for the welfare, benefit &amp; happiness of human
&amp; divine beings,' he would rightly be speaking of me.