Sure, the gravity affects Natsu, why wouldnt it? Natsu was in its area of affect. The question is how much does it affect Natsu? The answer of course being barely at all, to the point where its barely noticeable. So yeah,
i did see the lines around Natsu that shows he is affected by Bluenote's gravity, i simply
acknowledge the fact that it really only affects him about as much as Natsu's FD roar affected Bluenote on Tenrou. You know, this one.
You see how the fire is affecting Bluenote right there? Yeah well thats a rough equivalent to how much Bluenote's gravity affected current Natsu in their fight.
Yeah, they can, every top tier can beat Bluenote with ease, the only top tier you could argue couldnt is Neinhart, and even he easily does by summoning Hades to low diff him.
Every other spriggan has an even easier time,
Good guy top tiers like DF Gajeel, Laxus, Gray, Jellal all oneshot him casually because they are all on base Natsu's level or above.
Even Makarov destroys him in Titan mode.
Mira's MP is comparable to Makarov so she easily laughs off gravity too.
The simple fact that Erza can tangle with Azir and survive, means that she can easily walk through Bluenote's gravity unhindered. She doesnt need any sort of counter, she can simply overpower him with pure strength and slaughter him in CQC.
Besides, the only people Bluenotes gravity has an affect on is fodders he is way stronger than, people close to his level like Gildarts was can laugh off his gravity with ease. All FT top tier>Tenrou Gildarts so they can all walk freely under Bluenote's gravity.