I largely agree with esoterik's answer, however would like to elaborate on the strict number advantage, which I feel is the more accurate analysis and describes the inherent differences between player numbers in the format better without making assumptions about their skill level (which is how I read the question).
Basic Analysis of the Draft Format
The entire draft format is based around the principle that each player picking one card at the time yields better results than simply building a deck out of a set number of packs. This is demonstrated in the Sealed format providing six packs (so, twice as many as in a draft), yet requiring the same deck size in the end.
This is because you get to scroll through each pack, taking the card that works out best for you, while passing the rest, whereas in a Sealed event, you have to scrap a large portion of your pool because it's not in your color(s), the cards are simply unplayable, or you have way more than you'd like to play (also caused by the twice-as-large pool size).
This means that regardless how many cards are left for you to pick from, you always get to pick the single best cards, after each pack ending up with the 15 best cards from every hand instead of just 15 random cards from any booster pack.
Having more packs at the table results in more valueable individual picks
In a draft format, because you're looking at packs you've seen before, the total number of different cards you see changes with the amount of players. Since more cards mean more choices, in theory each player will get a better hand, as they get to choose their best 15 cards out of a bigger total number of cards.
Assuming a 15-card pack, these are the total amount of cards every player gets to see over the course of the draft:
- 8 Players: 276 cards (15+14+13+12+11+10+9+8)*3
- 7 Players: 252 cards (15+14+13+12+11+10+9)*3
- 6 Players: 225 cards (15+14+13+12+11+10)*3
- 5 Players: 195 cards (15+14+13+12+11)*3
- 4 Players: 162 cards (15+14+13+12)*3
More players in a pod will draft more Rares/Mythics
There's a certain ratio of Mythics to Rares (to my knowledge, it's about 1 Mythic in 8 packs, which we'll use as an example ratio, regardless whether it's accurate). A pod with 8 players will therefore have an average of 3 Mythics (24 total packs), while a pod of 6 players will only get 2.25 (18 packs). Whether this affects the overall quality of decks depends on the actual cards drawn, but since Mythics are arguably stronger cards than rares most of the time, this is a fair assumption.
While the number of packs scales with the amount of players (for each player, there's 3 packs), there are always five base colors in Magic, which players will need to negotiate between. In a pod of five, that averages to one color per player, six is close to that ratio, however for 8 players, this means that more colors are being necessarily shared.
In reality, every player is likely playing multiple colors even in smaller pods because it's unrealistic to be the only person in a specific color. With more players, however, more people will inherently be interested in any color.
This is the only factor that doesn't clearly favor a bigger number of players, however it's also the most insignificant one, as it's an intended concept of Magic The Gathering to have multiple colors in a single deck, and editions that need it will provide mana fixing.