Yes, as an IB/Affiliate you also earn IB/Affiliate lot commissions from your sub-affiliates and their client networks.
Direct clients: $8 per lot
From level 1 Sub-IBs (your 2nd level clients): $2.40 per lot
From level 2 sub-IBs (your 3rd level clients): $1.60 per lot
From level 3 sub-IBs (your 4th level clients): $0.80 per lot
This allows you to earn not only from your own referred clients, but also from the trading activity generated by your extended sub-affiliate structure.