Stake is currently at the southeast corner of the first floor. The stairs leading to the second are mostly in front of him, and he could leave cover and reach the stairs in 1 pass. There are some yakuza on the ground, though most of the club goers have fled. The yaks would constitute difficult terrain, but Stake doesn't think they'll put up any fight by the looks of them. You could send the bartenders either out the front door -- where they would have to leave cover and traverse quite a bit of open flooring until they reached the exit, or he could direct them down the stairs toward the basement, where they wouldn't leave cover for long at all.
Stake could also head to the southwest stairwell, keeping mostly under the balcony, and neither he nor the armored yaks would have shots, unless the armored yaks back-tracked to get them.
As for the 3rd vampire, no signs yet.