Hello Abhishek Gupta. Thanks for contacting Careers360 and we hope we will be able to answer your query. 

1. Cutoffs for direct PhD into IITs:

• https://www.quora.com/How-do-I-get-admission-into-a-Ph-D-program-through-the-GATE-exam-after-my-M-Tech-degree
• https://www.quora.com/What-GATE-score-is-required-for-direct-PhD-program

2. Cutoffs for direct PhD into IISc:

• https://admission.aglasem.com/iisc-bangalore-ph-d-admission/

Hope these links help you and all the best!