If we are talking in programming point of view the answer is “Yes”. If you are a programmer then you can understand easily that the admin team can always access the database. Same way all our mails are stored in a database on Google server, so it is accessible by the Google administrators.
Christopher Cuong Nguyen who was earlier responsible for Google Apps operations at Gmail shared the following lines at quora.com -
”A small number of GMail-related engineers have access to the servers as a matter of necessity to do their jobs; a very small number of people actually access the contents as a matter of necessity to do their jobs, and even then, almost always only the associated metadata. The rest have to file a request and justify any access they ever need, which is extremely rare. All have to sign paperwork re users’ privacy at the risk of dismissal and legal action, knowing that whatever they do is discoverable. And ultimately, an internal culture of respecting users’ privacy helps keep one another in check.”
So don’t worry we can trust Google and use Gmail because that people always keeps its identity.