My impression (based on nothing more than anecdotal industry experience) is that there are far more jobs for PHP globally, and that the average starting salary for a new PHP dev is going to be considerably lower than the average starting salary for a new Go dev.
However, the number of stable senior PHP dev jobs with high salaries is also likely far higher than for Go.
I imagine it's easier to earn more as a new Go developer if you can get a job doing it, but it's easier to steadily get raises as a PHP developer.
[0] https://insights.stackoverflow.com/survey/2018/#work-salary-...