Yes, you can get WiFi in certain parts of Cuba, particularly at hotels in cities like Havana. However, it will generally always cost you, and oftentimes WiFi is only available in hotel lobbies, not necessarily in rooms, and typically not in casa particulares (private homes). One way to get internet in the country is to buy cards from an ETECSA telecommunications centre, but prepare to wait in line for these. The papers allow you an allotted amount of WiFi time. The cards I purchased for a few CUCs all offered one hour of internet each. You can use them more than once — just make sure to log off WiFi when you're finished using yours, and whatever time you didn't spend will be leftover for your next login.
That being said, the speed of WiFi can vary, even once you get it. Overall, I had relatively reliable service, depending on where I was (countryside vs. city) and was able to check emails, upload photos, and even watch GIFs and videos. Still, as with anything in Cuba, go with the flow, because you might not always have the fast service you may be used to. Embrace it and allow yourself time to enjoy being unplugged!
Image Source: POPSUGAR Photography / Hilary White