It's almost not happening anymore because the whole esports industry thing is getting wider and wider as it goes by so, the athletes or mainly the competitive and professional players are serious with their careers and won't allow themselves to be involved in this kind of scheme.
The teams or players that becomes part of this scheme lately are the rising talents or in short, the newly born talents with potential and it's been put into waste.
I guess match-fixing still occurs, it's being done pretty clean nowadays so that nobody can assess that kind of scheme. Not only in CS:GO, but also in other eSports tournaments, particularly in MOBA. Before they qualify for an international competition, every region competes for a slot. So if a strong team is able to exploit the entire bracket by match-fixing, they will select which team to represent the country with them in the international tournament. It's a cheap tactic to be used due to the extreme desperation of winning an international league with a huge pot.
It still occurs but chances are slimmer these days. If the players involve plans to get in to the competitive scene, they will not create a ruckus like this that they will regret forever.
I have witnessed a lot of talents that do have the potential but suddenly fell into the pit because of not thinking doing this. This is for the other e-sporting events that I also play.
Well, due to the current ability of eSports players today, they can run it cleanly as what I said at some point, that is common for them and we really have no clue about it. Being an eSports professional is a short-term profession because they won't be a pro gamer in their whole life, some eSports careers are just 3-4 years out, so it's easier to be realistic and do their best in the league.