How would you pitch AWS to your CIO?

For what problem are you trying to solve? How does AWS best solve that business need? That's how I'd pitch it.

From the Perspective of CIO,  he needs to oversee Company's growth in process and technology.

AWS is highly matured cloud provider, providing range of technologies to achieve scalability, availability, security, compliance, backup, storage, AI and a lot more.

Any organization may have Trillions of data, but most important is the safety of that data, AWS is very good at it. You will have IAM architecture where every person is given only fixed set of authority.

If you have legacy application working only on your premise, you may feel difficult just once, but you have migrated to AWS cloud things will get pretty easy.

AWS is a well know, reliable, secure cloud platform. It is also the leader, and they provide all related tools and services to help us serve our needs and our clients. Their main competitor is Microsoft Azure, ensuring that there is a healthy motivation to offer the best services.

I guess it depends on your business case, to reduce your on-premise footprint, increase your computing capability for data analytics or have a partner that has a fully compliant/managed infrastructure that can reduce your risk/compliance requirements. 

Depends very much on the context...

Is your organization already using another cloud IaaS or PaaS, and you are advocating for a switch to AWS? 

Are you an on-prem, collocated or managed data centre operation advocating for a migration to AWS? 

Are you thinking about migrating existing workloads or using AWS for a completely new workload? 

What skills are available in your organization? Would you need to reskill your entire team? 

Some approaches to pitching it might apply across various situations; articulate how AWS would specifically address the CIO's (or any stakeholders') goals around security, cost management, compliance, agility and innovation, etc.