Was it actually said at any point this amateur tournament is supposed to come with any rewards, that aren't at best a trophy and an energetic handshake? Since EK said this whole subquest was purely optional, i feel doubt it's going to bring anything that'd considerably skew the balance of things in the long run -- if Ian had to participate and do well in order to afford things down the road then it'd make things quite far from optional. So i don't see this resulting in any big income spike.Ian presumably has two big income spikes coming up shortly though, much like Lena did if she commits to Seymour's path. Winning the tournament, and his promotion at Heirophant.
The promotion is similarly not something i'd bank much on. It's still a relatively low level job, and it might come with something like +1 salary increase (or maybe slightly higher, but that's getting counter-balanced by high rents if Ian is serious about moving out and getting his own place) and nowhere near what one can get paid to prance around naked and stick vibrators in one's orifices for exclusive amusement of a rich old pervert.