Well, no. Unfortunately. Confusing as hell. “VA” and Watts can be the same thing. But for some types of electrical loads they aren’t. VA is equal to Watts when the “Power Factor” of the load is 1. A light bulb has a PF of 1. Computer equipment may have a PF that’s lower, this makes the UPS less efficient. It’s up to you to figure out if your load has a PF of 1 or not, which is something that’s not easy to do. So typically you would use the lower of the two numbers when sizing a UPS for a given load. But in both cases, these numbers are the maximum load the UPS can support, not how long it can support the load for.
The actual hold up time of the UPS is a little more work to figure out. Usually, you have to check the manufacturer’s specifications for the particular UPS you’re looking at, and then do some math.
The UPS Kevin linked to is rated for 2 minutes at full load. Assuming they mean 900W, the power-storage capacity of the UPS is 900W * 1/30th-of-an-hour = 30WH. 900W for 2 minutes is the same energy output as 30W for one hour. The printer draws 65W (though I suspect in practice it’s only drawing that peak occasionally and the average is lower) so it would nominally last for 30/65*60=27 minutes with this UPS…