Here is a list of the maps you'll play in each game mode for Halo 5 come launch day.
(via Halo Waypoint)
Warzone - 24 players with REQs and AI enemies
• Escape from A.R.C.
• Raid on Apex 7
• March on Stormbreak
Warzone Assault - Destroy/defend a Power Core
• Dispatch
• Array
• Summit
Team Arena - Various modes
• Gambol (Breakout)
• Trident (Breakout)
• Coliseum (Slayer)
• Eden (Slayer)
• Plaza (Slayer)
• Empire (Slayer)
• The Rig (Slayer)
• Coliseum (CTF)
• Truth (CTF)
• Fathom (CTF)
• The Rig (Strongholds)
• Eden (Strongholds)
• Empire (Strongholds)
Slayer - TDM
• Coliseum
• Plaza
• The Rig
• Truth
• Regret
• Fathom
Breakout - Single life elimination
• Gambol
• Trident
• Trench
• Crossfire
• Altitude
Free-for-All - DM
• Eden
• Regret
• The Rig
• Plaza
• Orion
• Pegasus
SWAT - Headshots
• Eden
• Regret
• The Rig
• Plaza
• Orion
• Pegasus
Weekend Social - Changes weekly based on community voting
• Escape from A.R.C.
• Raid on Apex 7
• March on Stormbreak
Warzone Assault - Destroy/defend a Power Core
• Dispatch
• Array
• Summit
Team Arena - Various modes
• Gambol (Breakout)
• Trident (Breakout)
• Coliseum (Slayer)
• Eden (Slayer)
• Plaza (Slayer)
• Empire (Slayer)
• The Rig (Slayer)
• Coliseum (CTF)
• Truth (CTF)
• Fathom (CTF)
• The Rig (Strongholds)
• Eden (Strongholds)
• Empire (Strongholds)
Slayer - TDM
• Coliseum
• Plaza
• The Rig
• Truth
• Regret
• Fathom
Breakout - Single life elimination
• Gambol
• Trident
• Trench
• Crossfire
• Altitude
Free-for-All - DM
• Eden
• Regret
• The Rig
• Plaza
• Orion
• Pegasus
SWAT - Headshots
• Eden
• Regret
• The Rig
• Plaza
• Orion
• Pegasus
Weekend Social - Changes weekly based on community voting
(via Halo Waypoint)