As a general rule Google has an excellent uptime track record (how long their service remains operational). Unfortunately, Google Drive is currently experiencing issues for a very limited number of users, 1.5% to be exact.

All of my accounts seem to be working and Google has acknowledged the issue and is activly working on a fix. If you do have the issue you will see this error message if you try and connect “The server encountered an error. Please try again later”.

With Googles push into the enterprise outage such as these can significantly affect busines customers, here’s hoping they get back up soon

We will update you when Google has resolved issue or you can track their progress yourself.
Google has advised the issue has now been resolved:

The problem with Google Drive should be resolved. We apologize for the inconvenience and thank you for your patience and continued support. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better.

Source: Google.