Yes, OMGF Pro is compatible with Avada. The free version of OMGF isn't, due to the way Avada includes Google Fonts into the theme.
First off, you need to make sure that Avada doesn't use its own local storage method (it's kind of faulty and doesn't load all fonts locally):
Go Avada > Options and use the search bar to locate the options.
Set Google & Font Awesome Fonts Mode to CDN. Make sure you click Save Changes.
Second, change CSS Compiling Method to File.
In older versions, different configurations were possible. They still are, but I recently discovered that, in v7.11.3, setting this option to Disabled causes a bug making font weights not render properly.
Setting it to File is the most performant and safest option.
After this, make sure that OMGF Pro's Advanced Processing (Pro) (located under the Detection Settings tab) option is set to Process Local Stylesheets. Or, just enable OMGF Pro's Auto-Configure Adv. Processing setting under the main Local Fonts tab.
Now, hit Save & Optimize in OMGF Pro's settings screen and you're good to go!
That should do it!