Yes, GST is applicable on the landlord's 30% revenue share. Renting land for commercial use is a taxable supply of service. If the landlord's total annual turnover exceeds ₹20 Lakhs (or ₹10 Lakhs in hilly/special states), they must register for GST, charge 18% GST on their 30% share of the revenue, and remit it to the government.