Ruff, Underdog Champ

• WOTC Official Reminder Textofficial rules
  Lifelink — Damage dealt by this creature also causes you to gain that much life.

• WWizards of the Coast2019-11-12
  Official Ruling
  Once Ruff is revealed in any zone, for the rest of the match, any spell or ability that references the Hound creature type instead references the Dog creature type and all Hounds are Dogs instead. This isn’t a type-changing or text-changing effect. It’s simply time-traveling errata that has been, will have been, or may will be issued.
• WWizards of the Coast2019-11-12
  Official Ruling
  If a game in a match is a draw, no player lost that game, even if the game was a draw because both players lost the game at the same time.

Rulings via Scryfall