which train? origin? destination? in general it varies...what i know is~
1 10% to 30% of all seats for tatkal depending on popularity
2 2 berths/coach for ss/lb quota...
3 if sl is lowest class then few seats for #ladies quota on some trains
4...
more... some seats for duty pass, out station, day night, foreign tourist, parliament house, and other obscure quotas
5 10 to 25% of seats for ho quota
6 some for remote location/pooled/road side quota
7 rest for general quota...varies from train to train...