Yes, this is an interesting thing. There's an obvious (to the DM, reading) connection between this monster and the gargoyle statue in area 11 (to come). The blue quartz gems from this creature's collar will fit the palms of the gargoyle statue, to potentially, eventually produce a gem of seeing. If the PCs come to this room before getting to 11, they can possibly deduce a connection, and possibly think of using the gems. This serves as "a thinking person's" clue. Good.
But, if the PCs [correctly?] use the arch at area 5, they will appear in area 11, bypassing this area 8, and so will be standing before the gargoyle statue without the area 8 clue (or gems). Hmm. Kind of hard to call this. Arguably, if they do the right thing in area 5, they have no clue for area 11. If they take the hard way (deconstructing their way) through area 4, they will pass through area 8 and get a clue for area 11. So is digging through area 4 the right/better answer than figuring out the Simon Says archway at area 5?
And then the cryptic clue, "Look low and high for gold, to hear a tale untold. The archway at the end, and on your way you'll wend." I agree with Stoat -- I don't know what this refers to, either. I see there are some things it might refer to -- the gold orb in the area 10 hallway, and there are at least 3 archways after this clue -- but the riddle makes no sense in relation to them.
Either this is a clue that even the DM reading the module (probably?) might not understand, or it's a false clue not meant to be followed. If it is a real clue, it is too unclear. If it is false, then this is an example of punishing, (or at least counter-rewarding), attentive and thorough PCs.
And finally, looking at the stats for the gargoyle, here: this is another example of Gygaxian stream-of-consciousness writing style.
Tomb of Horrors said:
This monster is a huge (H.P.: 64; 19 strength) monstrosity that attacks 6 times/round as a 12 hit dice creature inflicting damage as follows: 2-8 x 4/3-12/1-6, and if any 2 of the clawing attacks (2-8 x 4) hit, the creature will do an additional 7 hit points of rending damage to the opponent so struck.
I know this is a very early-era module, but other modules of its day used better, more concise stat blocks.
Simple Edit said:
This monster is a huge monstrosity (AC: 5, HD: 12, HP: 64, Attacks: claws x4/bite/horn, Damage: 2-8 x4/3-12/1-6, if two claws hit add 7 more damage).
Bullgrit