They just announced that at least 70 locations will remain open. Here is the article
http://www.al.com/news/index.ssf/2017/05/gander_mountain_closures_3_ala.html
and here is the list of stores that will remain open (at least for now)
Alabama
Florence
Opelika
Tuscaloosa
Florida
Jacksonville
Ocala
Palm Beach Gardens
Georgia
Albany
Augusta
Newnan
Valdosta
Illinois
Marion
Peoria
Springfield
Indiana
Avon
Evansville
Greenwood
Kentucky
Bowling Green
Michigan
Flint
Grand Rapids
Marquette
Saginaw
Minnesota
Forest Lake
Lakeville
Missouri
Chesterfield
Mississippi
Hattiesburg
North Carolina
Greensboro
Winston-Salem
North Dakota
Fargo
New York
Cicero
New Hartford
Ohio
Huber Heights
Reynoldsburg
Pennsylvania
Chambersburg
Greensburg
Williamsport
York
South Carolina
Myrtle Beach
Tennessee
Jackson
Mount Juliet
Texas
Amarillo
College Station
Fort Worth
Tyler
Virginia
Roanoke
Wisconsin
DeForest
Eau Claire
Franklin
Kenosha
Onalaska
Roithschild