If it already has an IR remote and, as @Ryan780 Said, it’s not a gas fire, it’s just a light show, usually the easiest way is to integrate it with a Harmony home hub. That in itself will give you Google home or Amazon echo integration. Then there’s an official SmartThings/harmony integration which works well and give you all the other automation options. 
I use this at my house for electric candles, for example.
You can check the Harmony database to see if your device is already listed there, but if it has an IR remote you could probably use it even if it isn’t in the database, it’s just more work to set it up.
There are some other methods as well, see the FAQ (this is a clickable link)