It's impossible to say with much certainty one way or the other but Sony has a very consistent track record. Unlike anyone else Sony is the only company to have never had a home console failure in terms of sales, so even without knowing anything you can put a fair bit of confidence in their next system based on history, as the ps5 will be a home console after all. Sony has the best track record.
Switch is performing well above the average Nintendo System however, it's already a proven success. PS5 isn't proven, even if history would tell us it probably will be.
PS1: 104.25m, PS2:157.68m, PS3: 87.41m, PS4: (120m?), AVG:117.35m. That's a very strong precedent.
I'd give a 60:40 chance in favour of the PS5 beating the Switch. They're coming from a very strong position to launch their next console so as long as they don't say $599 USD it should do very well.
Switch - ~100m
PS5 - 75m-150m.
LTD Sales Predictions: PS4 - 130m, Switch - 110m, XBO - 52m
2019 Sales : PS4 - 15m, Switch - 18.8m, XBO - 4.8m
2020 Sales: Switch - 22m (Peak Year)