I'm planning to get to YYZ from GVA via DUB, and Aer Lingus handles both legs. The layover time is just one hour, and I have no experiences in flying with Aer Lingus. Is the one-hour time sufficient to catch the second leg?
Should be ok. If you bought this as a single ticket then it's a legal connection and the airline will take care of you, if you miss it (unless it's your fault). This being said, the official website of Dublin airport lists the minimum connection time as 90 minutes. See https://www.dublinairport.com/flight-information/connections/connection-guide, so it's certainly on the tight side.
What will help in your case, that you probably don't have to deal with any type of security, immigration or pre-clearance since Ireland is a non-Shengen country and your not going to the US it's a simple international transit.
Is one-hour layover sufficient at DUB airport?
No connection is ever guaranteed. You can only estimate the likelihood that you'll make it and assess what happens, if you don't. In your case, if all goes "normal" you are likely to make it. If your incoming is delayed, if you have mobility issues or if something else unexpected happens, you won't.
There is not a lot of room for error here, so preparing would help. Take a look at https://www.dublinairport.com/docs/default-source/flight-timetables-and-schedules/dublin-airport-flight-connection-guide3b5fbdcccf5e4d34858f630d86795513.pdf?sfvrsn=e983b36f_4 and familiarize yourself with the process and the layout of the airport and the gates. I'm guessing that you'll need 10-15 minutes to get off your flight and figure out where you need to go and another 15-20 minutes to actually get there, so you'll have a 10-15 minutes before boarding closes (typically 15 minutes before departure).