though there is a formula but i dont remember it.
but heres the method which i have developed for calculating the enthu of my team-
case 1-when you are alive in the cup
for every TIE the enthu for the next game will be 1 more than the enthu for the last game(this works fine till your enthu reaches 11,but sometimes the enthu stays at 11 despite TIEing the last game)
for every normal your enthu will be 1-2 less than the enthu for the last game(depending on the sublevel of enthu)
for every CT your enthu will be at 4(if the enthu of the team is 8 or less for the last game) or 5 (for enthu of 9 or 10) or 6(for enthu of 11 or 12)
case 2-when you are out of the cup
for every TIE in tuesday's game your enthu for saturday's game will be equal to that of tuesday's game.and for every TIE in saturday's game your enthu for tuesday's game will be 1 more than that for saturday's game.so if you TIE both the games of a week,your enthu will increase by 1.
for every normal in tuesday's game your enthu for satuday's game will be 2-3 less than that of tuesday's game.and for every normal in saturday's game your enthu will be 1-2 less for tuesday's game(again depending on the level and sublevel of enthu)
but of the enthu of your team is 6 and you play a normal then your enthu will either be at 6 or drop to 5(depending on the sublevel)
for every CT in tuesday's game your enthu will be close to 5 for saturday's game(high 4 or low 6 or exactly 5).
its a bit silly but is a dependable method for calculating the enthu for your next game.