Upgrading seats or stadium is the same thing...

I am also at lvl 7 and with a stadium of 31k capacity, I got ticket price at 14$ for league matches and 18$ for championsleague. Both give me a solid 27k each match (3% possession)
Today I only played a championsleague match and got around ticket sales at 490k and merchandise at 146k.
Ofcourse my remaining facilities are lvl 7 minimum.