I lived in Guanajuato for 5 years (2009-2014) and played music professionally there that whole time. I played mostly jazz and classical music but I also did some gigging with a group that played some more rock type venues. Here’s a breakdown by genre:
Classical: There are a number of places offering regular concert series of classical music. Several museums have weekly series, the Casa de Cultura has regular events and also coordinates statewide tours, the Festival Cervantino presents local performers each year as well. The state symphony is based in Gto as well so there are concerts put on by offshoots of that organization too.
Jazz: There are a couple of small venues that have jazz on a regular basis – pay is poor but they let you do what you wish and people do come out to listen. Also, almost all of the museums and cultural organizations I mentioned above present some degree of jazz along with the classical offerings. Again, sometimes pay can be pretty good.
So the good news is that for “art” music like classical and jazz it is a pretty good scene and the pay is not too bad in most cases. Sometimes it is quite good. You need to be a very good musician though, because the symphony brings serious players from all over the world. Gigs are earned on merit rather than “how many tickets can you sell” like in the US because the venues have a governmental budget and they want to fill their series with excellent concerts. Luckily for me, this is mostly what I play so it worked well (even though I sure still love to rock out from time to time!).
Now for the bad news if you want to play anything other than “art” music…
Rock/Pop: There are a few venues that are happy to let you play for free or for the door. There used to be one that paid a decent rate but they sold to a new owner and that’s over. There is no government money for pop music, so if you want to earn any money, you have to find or create your own gigs. It’s mostly cover bands that aren’t so good that play around town in the few bars. If you want to do original music it is a very tough row to hoe. Simply finding a place to play original music is hard enough but getting any pay is almost impossible.
After saying all of the above, I will tell you that now that we have moved back to Mexico, we decided to move to Queretaro instead of returning to Guanajuato. The scene in Gto. is a little small and provincial feeling and both Queretaro and San Miguel de Allende have larger scenes and more options for musicians. I had fun in Guanajuato and still adore the city but I found being the big fish in the small pond limited my options a little too much and since Guanajuato is only 90 minutes from Queretaro, I can still easily return to play concerts on a regular basis.