The only inspiration I know is that Kurt wrote a song called I hate myself and I want to die and Noel wasn't having it so he wrote a song called live forever, the rest is as you say history.

'The Dying Of The Light' chorus = 'In Bloom' chorus

I think understanding and appreciating how important Nirvana was at the time depends on your age. Guys like you and me witnessed it first hand in Ameirca. The first CD I ever bought was Nevermind. The end of the 80s and very early 90s were filled with cheese music. Hair bands and such. Nirvana made Guns n Roses look like the Bee Gees. Things were about to get interesting in America. Bands like Pearl Jam, Nirvana, Smashing Pumpkins were about to rule the charts. Happy times.

No way, that scale, those harmonies are so kurt cobain...

No, my point overall is 100% fucking right.
Don't miss the point.

Eh, 50/50.

Nirvana were an influence, clearly. Especially, in the early days when that stuff was comparitivly new. Noel said so, and still praises Nevermind from 1991, and talks about how Definitely Maybe wouldn't be so heavy without it. Plus, there's "Married With Children" which clearly had a slight nod to "Lithium", and "Talk Tonight" ('I'm on a plain, I can't complain', a near-identical lyric to Nirvana). Nirvana didn't invent the 'quiet loud' thing, but they certainly amplified it and brought it to the mainstream, hence you hear those kinds of sounds in "Champagne Supernova".

But the rest of grunge? Not so much, I can't see Noel or Liam shooting up to Alice in Chains somehow. I think Noel despised Courtney Love's band Hole. Liam went on about how he disliked grunge immensely, and I think he had a row with a kid wearing a Pearl Jam shirt, who asked for Liam's autograph.
On the other hand, Noel thinks enough of the Smashing Pumpkins to tour with them, like he did in 2019.

If anything, Oasis saw grunge and all the kids listening to these American bands on one side, and mindless dance music on the other, and they saw a gap in the market for British guitar rock in the tradition of Beatles/Stones/Who/Kinks/Zeppelin, which they went ahead and filled.
At that, they did share a few influences with grunge, obviously the British stuff like 60s psychedelic and the Beatles and later Led Zep, punk rock/Pistols, plus of course the Doors, Stooges, and the Godfather himself Neil Young. That probably contributed to some of the similarities, even if those influences often manifested themselves in different ways. And Oasis were rarely introspective or brooding like grunge bands usually were, different lyrical approaches entirely. 

Grunge may have influenced them as far as the context of the time was concerned, it still meant a lot to people at the time DM was released (see how Bush took off in the States around the same time), so perhaps they played heavy partly to tempt grunge fans towards their stuff? The fact that as late as 1995, you had tracks out like "Morning Glory" which were quite rock-heavy, suggests they still felt a need to compete with the grunge thing.

TBH, if you made a compilation out of the heavier side of Oasis; think "I Hope, I Think, I Know", "Morning Glory", "Fucking in the Bushes", "Slide Away", "I Can See A Liar", "Acquiese" plus the moor broody ballads "Half the World Away", "Married with Children" - you'd have a pretty good grunge-era album.

In terms of that contemporary rock sound of the 90s, you can definitely hear the Nirvana comparison in Oasis. That loud, raw and dirty sound. Oasis success was primarily down to old fashioned hooks and melody with a raw contemporary guitar sound.

Would have been useful if they'd kept that Nirvana style ragged edge to their music but everything after Be Here Now was too safe sonically. The more Oasis retreated into influences that didn't go beyond the 60s and 70s, the more derivative they became.

Indeed, everything from Heathen Chemistry onwards sounds like it was recorded in the 1960s, something Noel's solo career indulges in far too often. That's not a compliment.