If statement - multiple actions

One way would be to use pivot and unpivot.

Basically

Add an RowKey index (unless you have a key for the rows)

unpivot the answers

Remove the blanks

Group and Rank Rows by RowKey

Unpivot by a a Column based on Rank

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcspPUtJRAiKvzFwg6ZJYlqoUqxMNEoFIuSSWpIJUgAQhauBSSrGxAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Answer1 = _t, Answer2 = _t, Answer3 = _t, Answer4 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Answer1", type text}, {"Answer2", type text}, {"Answer3", type text}, {"Answer4", type text}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1),
    #"Unpivoted Columns" = Table.UnpivotOtherColumns(#"Added Index", {"Index"}, "Attribute", "Value"),
    #"Filtered Rows" = Table.SelectRows(#"Unpivoted Columns", each ([Value] <> "")),
    #"Grouped Rows" = Table.Group(#"Filtered Rows", {"Index"}, {{"AllRows", each _, type table}}),
    #"Invoked Custom Function" = Table.AddColumn(#"Grouped Rows", "Rows", each fnRankTable([AllRows])),
    #"Expanded Rows" = Table.ExpandTableColumn(#"Invoked Custom Function", "Rows", {"Attribute", "Value", "Index.1"}, {"Rows.Attribute", "Rows.Value", "Rows.Index.1"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Rows",{"AllRows"}),
    #"Added Custom" = Table.AddColumn(#"Removed Columns", "Answer", each "Answer" & Number.ToText([Rows.Index.1])),
    #"Removed Columns1" = Table.RemoveColumns(#"Added Custom",{"Rows.Attribute", "Rows.Index.1"}),
    #"Pivoted Column" = Table.Pivot(#"Removed Columns1", List.Distinct(#"Removed Columns1"[Answer]), "Answer", "Rows.Value")
in
    #"Pivoted Column"

fnRankTable

let
    Source = (SourceTable as table) => let
        #"Sorted Rows" = Table.Sort(SourceTable,{{"Attribute", Order.Ascending}}),
        #"Added Index1" = Table.AddIndexColumn(#"Sorted Rows", "Index.1", 0, 1)
    in
        #"Added Index1"
in
    Source

Another option is to merge the answers with a delimiter.

Remove starting and duplicate delimiters, then split it again.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcspPUtJRAiKvzFwg6ZJYlqoUqxMNEoFIuSSWpIJUgAQhauBSSrGxAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Answer1 = _t, Answer2 = _t, Answer3 = _t, Answer4 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Answer1", type text}, {"Answer2", type text}, {"Answer3", type text}, {"Answer4", type text}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1),
    #"Merged Columns" = Table.CombineColumns(#"Added Index",{"Answer1", "Answer2", "Answer3", "Answer4"},Combiner.CombineTextByDelimiter("|", QuoteStyle.None),"Merged"),
    #"Replaced Value" = Table.ReplaceValue(#"Merged Columns","||","|",Replacer.ReplaceText,{"Merged"}),
    #"Replaced Value1" = Table.ReplaceValue(#"Replaced Value","||","|",Replacer.ReplaceText,{"Merged"}),
    #"Added Custom" = Table.AddColumn(#"Replaced Value1", "Answers", each Text.TrimStart([Merged],"|")),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"Merged"}),
    #"Split Column by Delimiter" = Table.SplitColumn(#"Removed Columns", "Answers", Splitter.SplitTextByDelimiter("|", QuoteStyle.Csv), {"Answers.1", "Answers.2", "Answers.3"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Split Column by Delimiter",{{"Answers.1", type text}, {"Answers.2", type text}, {"Answers.3", type text}})
in
    #"Changed Type1"