支払日	128439	
支払い日	45179	
引き落とし日	14658	<-- sometimes shows up with articles on 支払日, date cash is taken from your bank account

ペイデー	188	0.0%
ペイデイ	878	0.1%

月給日	1211	0.2%
俸給日	82	0.0%
給料日	613549	76.3% <-- common "payday"

https://context.reverso.net/translation/japanese-english/支払日

https://www.cr.mufg.jp/mycard/knowledge/20041/index.html
クレジットカードの引き落としはいつ？締め日と支払日の仕組み

I just had occasion to look at all the "payday"/"pay day" entries, and this seems quite unlike the others. In particular, 給料 is receiving, 支払 feels like "paying". I.e. this is a "payday" only from the employer's perspective.

The most common use of 支払日 seems to be on a credit card statement.

eijiro has:
賃金の支払日
payday〔不可算〕
and
給与の支払日
payday〔不可算〕

But I think, again, this is from the employers perspective?

Here's a site from a business regulation point of view, saying when you are-and-are-not allowed to set your employees pay day.
https://jsite.mhlw.go.jp/tokyo-roudoukyoku/yokuaru_goshitsumon/tingin/q4.html
Q4.賃金の支払日を「月の第4金曜日に支払う」と定めてもよいでしょうか？

On another site, google translates this:
ほとんどの会社は月に１回の給与の支払日を決めていて
as:
most companies set a monthly salary payment date and pay your salary accordingly

I think this is more appropriate here than "payday".

@@ -5 +5 @@
-<keb>支払い日</keb>
+<keb>支払日</keb>
@@ -8 +8 @@
-<keb>支払日</keb>
+<keb>支払い日</keb>
@@ -15 +15 @@
-<gloss>payday</gloss>
+<gloss>payment date</gloss>