Q: I submitted a research article in an Elsevier journal about seven and half months ago . How long I have to wait for editor's decision?

Detailed Question -

I submitted a research article in a Q1 journal of Elsevier on Oct 20, 2020. Then after 15 days, we received the first round of reviewer reports. After revision, we submitted our revised manuscript (R1) on Dec 14, 2020. From the editorial manager account, we can see that the status of our revised manuscript is "Under Review" and it remains unchanged from Jan 02, 2021. Actually, it's a long period we are waiting for the editor's decision on our revised manuscript.
How long I have to wait for an answer? What should I do in this situation?

No answer yet