As it stands now, someone who already has a subscription cannot be gifted a sub; even of a higher tier.
Piggy-Backing off the idea of upgrading someone from Tier 1 to a higher tier, perhaps be able to extend their "current" sub length at the current tier; Twitch by all rights should know when a sub is going to expire, so the gifted sub could be added to end of the existing one. -"user" just gifted you an additional 3 months on your subscription!".
As it stands now, someone who already has a subscription cannot be gifted a sub; even of a higher tier.
Piggy-Backing off the idea of upgrading someone from Tier 1 to a higher tier, perhaps be able to extend their "current" sub length at the current tier; Twitch by all rights should know when a sub is going to expire, so the gifted sub could be added to end of the existing one. -"user" just gifted you an additional 3 months on your subscription!".