The Venetian has announced that they have canceled all their hotel reservations through May 31st. The Venetian has also announced that it is taking care of its employees by paying them at least through May 17th. By saying at least through May 17th it also indicates that could be extended as needed.
The Venetian right now is looking at a June 1st opening but that is subject to change. When Las Vegas can reopen depends when the Governor of Nevada removes the shutdown order currently in place because of the pandemic.
After the shutdown order is removed by the Governor there will still be a little time before the resorts will be able to be reopened: The casinos will have to satisfy the Gaming Commission before they can reopen and, the resorts will have to get their employees back to get things going again.