Quicksilver Gargantuan

Except for its power and toughness, Quicksilver Gargantuan copies exactly what was printed on the original creature and nothing more (unless that creature is copying something else or is a token; see below). It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, or so on.

If Quicksilver Gargantuan is not a creature (for example, if it entered as a copy of an animated land), it will not have the characteristics of power or toughness at all, so it won't be 7/7. If it later becomes a creature, its power and toughness will be determined by the effect that causes it to become a creature; again, it won't be 7/7.

Any "enters" abilities of the copied creature will trigger when Quicksilver Gargantuan enters. Any "as [this creature] enters" or "[this creature] enters with" abilities of the chosen creature will also work.