I've seen a lot of poker odds charts like this that specify a hard-coded value for odds based on outs. Is the chart agnostic of the number of players? Wouldn't my odds be greater if there were only 2 players (a large remaining deck) vs 20 players (a small remaining deck)?
The number of players doesn't matter when calculating odds.
The thing is, at the flop you have seen 5 cards, and there are 47 you haven't seen. It makes no difference at all if those unseen cards are held by other players, or in the deck.
Your hand is 6 and 8 offsuit. The flop comes down 7, 9, 2 rainbow.
You have a straight draw with 6,7,8,9 Either a 5 or a 10 will give you a straight.
8 outs x 4 = 32% chance of hitting a straight.
If you have 2 opponents your chance of hitting the straight is 32%.
If you have 15 opponents, your chance of hitting the straight is 32%.
The poker odds charts are calculated strictly based on a random selection of the next cards. They don't take into account any information about the play to that point.
A player can therefore potentially do better, but there is by no means any "mathematical" way to express this. For example, if the flop is two spades and a non-suited connector, you could guess that people who stay in have cards that could make a hand out of them. And that might let you improve the calculation over the odds charts.
So if there were six players (you and five others) who all stayed in, the chances are great that somebody has a couple spades back. Or cards that will make the straight. So you might infer some information about the cards in other player's hands, and adjust your ideas about the odds for the next two cards. Especially if there is heavy betting.
However, you can't count on this. Anybody could be entirely bluffing. So you can't count on such calculations.