Sorry, this was a mis-reading of Skeletal Lord's ability. I thought it said "sacrifice 5 skeletons and play a card", not "exhaust 5 skeletons and play a card". Thus I thought there was overlap between Garth Torken's ability to sacrifice a skeleton an draw a card, and Skeletal Lord's ability to sacrifice 5 skeletons.
The question in this situation was
1. "would both Skeletal Lord's abilities be activated"
2. "If so, In which order would they be activated"
e.g. Do I activate Garth's ability 5 times, draw 5 cards, and then because 5 skeletons were sacrificed, activate Skeletal Lord's (mis-read) ability.
There are two options based on the distinction between these scenarios when it comes to "[Cost] -> [Ability]"
1. [Cost] is something performed by a card (exclusive) => "No, you don't get to draw 5 cards if you pay for skeletal lord's ability by sacrificing skeletons"
2. [Cost] is something fulfilled by the player, and fulfillment triggers the ability (potentially multiple) => "Yes, if you pay for skeletal lord's ability, you have fulfilled the requirement of Garth's middle ability, and get to draw a card 5 times"
From what @zhavier was saying, the current standard is option 1.