Hi@Abhishek,
You want to upload your zip file from s3 bucket to aws lambda function, for that you can use the bellow syntax.
To create one lambda function.
$ aws lambda create-function 
--function-name "awslambdausingcli" 
--runtime "pthon3.6" 
--role "arn:aws:iam::625297745038:role/lambdaapipolicy" 
--handler "awscli.handler" 
--timeout 5 
--memory-size 256 
--zip-file "fileb://awscli.zip"
To update that lambda function.
$ aws lambda
update-function-code
--function-name <value>
[--zip-file <value>]
[--s3-bucket <value>]
[--s3-key <value>]
[--s3-object-version <value>]
[--cli-input-json <value>]
[--generate-cli-skeleton <value>]
Try with this once.