Ehm, twitch has it's own donation system (which works trough paypal) e.g.: https://www.twitchalerts.com/donate/tsm_theoddone (and ofc boobies!) https://www.twitchalerts.com/donate/pink_sparkles

If you use a paypal link they also get the referrer unless you simply post your PP email and make people doit manually, but since the introduction of TA i think that's against the EULA.