Can we interchange phrases " What's the date today?" and "what day is it today?" [closed]

All of your sentences are correct, but may provide different answers.

What's the date today and What date is it today?

are the exact same question, and will usually give the answer 'March 8th'.

While

What's the day today and What day is it today?

are also the same question, but will usually give the answer 'Saturday'.

However, despite it being grammatically correct, I doubt you'd hear many people saying 'What's the day today?'

What is the Date today would technically mean you were asking the number of the day, like October the 18th. But if you were to say "What is the Day today" would make you be asking the name of the day, like Sunday.