When word leaked that Larry Gagosian was toying with opening a Madison Avenue restaurant below his art gallery, Upper East Siders wondered whether he’d relinquish his regular table at nearby Sant Ambroeus. But Gagosian’s apparently taking an “if-you-can’t-beat-’em, join-’em” approach by bringing in Sant Ambroeus to manage his under-construction eatery at 980 Madison Ave. The venue that temporarily housed a Damien Hirst “Spot Shop” will include more gallery space and a bookstore. Gagosian’s just returned from inaugural London art fair Frieze Masters, where his gallery nearly sold out its booth of Richard Avedon photos from the historic “The American West” series. Tomorrow Gagosian opens a 17,760-square-foot, Jean Nouvel-designed space inside a hangar at Le Bourget airport outside Paris, where collectors can step off private jets and start shopping. The opening, to coincide with Paris art fair FIAC, features work by Anselm Kiefer, while another Paris branch will show work by Rudolf Stingel.