Google integrated, but only to google drive and google calendar. You can open a Gantter project straight from google drive and you can sync your tasks to google calendar so you don't even have to go into your project to see what you have to do on any given day and that goes for anyone you assign tasks that has the project shared with them as well, not just yourself. 

There is a google comment like feature where you can communicate with your collaborators within a project and real time collaborate with as many people as you want in a project at any given time. However unfortunately there isn't a way to import or transfer everything over from your google sheet to a Gantter project. You can copy and paste stuff your project in bulk if you would like to go from CSV to gantter. Or export from gantter as a CSV file.