Auction link: Bildnis Elisabeth Lederer (Portrait of Elisabeth Lederer) - Gustav Klimt
The pre-auction estimate is listed as "available on request". I haven't emailed Sothebys myself, but it's widely reported (e.g., NYT) to be around $150 million.
Resolution details
Example from a past auction: This painting by Vigée Le Brun sold for 3,085,000 USD. This is the equivalent number I will use.
Note that the final listed sale price typically includes the buyer's premium (& potentially other fees). IIUC, the pre-auction estimates generally refer to the hammer price (hence, my $175 million over under should be close to the pre-auction estimate).
If it fails to sell, resolves N/A (AFAIK, this has a guarantee, so that may be impossible). If no sale price is listed after the auction (online or by other media sources), resolves N/A. But this is an important sale so I am sure there will be a price reported if it sells. And I will do my best to ensure it's inclusive of buyer's premium.
Details

One of the final, fully-formulated expressions of Klimt’s oeuvre, Bildnis Elisabeth Lederer has Elisabeth frontally placed, standing at center. Her gaze is direct and calm, unlike many of the aloof or dreamy women he captured looking beyond, or without regard for, the viewer. Here, Klimt reveals a fully self-possessed young woman, barely twenty years old. True to the sitter’s features, the face nonetheless bears the artist’s subtle touches, such as the tiny lines at either side of the mouth that turn her otherwise emotionless lips upward in an enigmatic smile. Any expression of self-consciousness is absent, though the rendering of her hands betrays restlessness if not a touch of angst. Venerated by the costumed figures who flank her, she is fantastically attired and wears a regal robe. The work’s symbolism through fashion is paramount to its conceptualization: her clothes project hierarchy and rank, contemporaneity and tradition, individual taste and worldly sophistication. The background’s atmospheric brushwork appears in brushstrokes at once distinct and melding, in ineffable tones of pale blues and greens mottled by passages of peach and rose pink. Every aspect of this painting, from the carpeted floor to the white flower atop her coiffure, from the halo of background figures to the dragon robe adorning her—not to mention the penetrating black of her eyes—was carefully envisioned to seize the viewer’s attention and imagination. (Lot essay)