If he hopes to make a profit - it's a dumb idea.
But since he is a billionaire, maybe he doesn't need to make a profit.
If it truly is an identical copy (plus modern technology) there will be no balconies and many, many inside cabins.
Quite a few cabins will have no bathrooms; you will need to share a bath down the hall.
A ship with this design requires a very high crew to passenger ratio. That equates to very high cruise fares.
As elegant as the original? That's what they are saying.
A First Class Ticket for the 5 day crossing on the original Titanic was US$2,000.
That year, the average American earned US$300 for the entire year.
This fellow claims he is marketing it to the Australian Cruise Market.
Good luck to him.