Gary Illyes from Google posted a DYK, did you know, recently on Twitter that said that generally GoogleBot "doesn't make use of cookies, but it can if it detects it cannot get to the content without them." So if your content requires cookies, GoogleBot may not be able to read the content but it likely will know that it can't read the content because of the cookies.
Here is the tweet with his friend:
DYK Googlebot generally doesn't make use of cookies, but it can if it detects it cannot get to the content without them? pic.twitter.com/UtEMg8g10n
— Gary Illyes ᕕ( ᐛ )ᕗ (@methode) March 20, 2017
Most SEOs probably know this but it seemed to have surprised quiet a few SEOs after he posted.
What does GoogleBot do if it is being blocked from content because of cookies? Well, maybe it looks for other ways in?
Forum discussion at Twitter.
Source: Search Engine Roundtable