Read file with over 300k words and filter through appropriate filter to return list of matching words
First off I'd change how you are making char1filter.
Here's what I'd do differently:


Remove the is True as it's implied.
Change the element.startswith('') to element[0] == 'a'.
Merge all the element checks into one, using in. element[0] in 'bptsmdcgfl'.
Use a list comprehension.


Merging all this together we should get:

char1filter = [
    element
    for element in lines
    if len(element) == 5 and element[0] in 'bptsmdcgfl'
]


Id however store 'bptsmdcgfl' with filterlist2, filterlist3 and filterlist4.
And instead just remove all element that aren't 5 long.

five_long = [
    element
    for element in lines
    if len(element) == 5
]


This leaves you with four roughly identical pieces of code.
And so I'd change all the filterlists to be a single list to loop through.
And then perform the transformations inside this.

data = five_long
for to_filter in filter_lists:
    data = [
        element
        for element in data
        if element[0] in to_filter
    ]
    print(data)
    print(len(data))


If however you just want the last filter list, then you can merge all the filters into one, and then do a single filter on that.

filter_list = [e for l in filter_list for e in l]
data = [
    element
    for element in five_long
    if element[0] in filter_list
]
print(data)
print(len(data))




You should also read PEP8 to style your code correctly, like I have above, which makes your code much easier to read.
You should also use with when opening files, tuple(open('')) is bad and should instead be:

with open('words.txt', 'r') as f:
    lines = tuple(f)




And so the code could be:

FILTER_LISTS = [
    ['b', 'p', 't', 's', 'm', 'd', 'c', 'g', 'f', 'l'],
    ['a', 'r', 't', 'h', 'i', 'v', 'o', 'y', 'l', 'e'],
    ['a', 'l', 't', 'o', 'i', 'n', 's', 'r', 'm', 'f'],
    ['a', 'm', 'd', 'k', 'e', 's', 'x', 'p', 'l', 'y'],
]

with open('words.txt', 'r') as f:
    lines = tuple(f)

data = [
    element
    for element in lines
    if len(element) == 5
]
for to_filter in FILTER_LISTS:
    data = [
        element
        for element in data
        if element[0] in to_filter
    ]
    print(data)
    print(len(data))